progression update for latest internal changes in Motion

9fd0e15e · Daniel Dahan · 3bc0ad78 · 9fd0e15e · 9fd0e15e · 9fd0e15e
Commit 9fd0e15e authored Dec 14, 2017 by Daniel Dahan
24 changed files
--- a/Motion.xcodeproj/project.pbxproj
+++ b/Motion.xcodeproj/project.pbxproj
@@ -7,15 +7,24 @@
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+		965FE9881FE304E70098BDD0 /* MotionTransition+Start.swift in Headers */ = {isa = PBXBuildFile; fileRef = 965FE9661FDD99800098BDD0 /* MotionTransition+Start.swift */; settings = {ATTRIBUTES = (Public, ); }; };
+		965FE9891FE304E70098BDD0 /* MotionTransition+Animate.swift in Headers */ = {isa = PBXBuildFile; fileRef = 965FE96E1FDEFA8B0098BDD0 /* MotionTransition+Animate.swift */; settings = {ATTRIBUTES = (Public, ); }; };
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@@ -31,7 +40,6 @@
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@@ -39,9 +47,9 @@
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 		96E4097E1F24F7370015A2B5 /* MotionSnapshotType.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96E409591F24F7370015A2B5 /* MotionSnapshotType.swift */; };
-		96E4097F1F24F7370015A2B5 /* MotionTransition.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96E4095A1F24F7370015A2B5 /* MotionTransition.swift */; };
+		96E4097F1F24F7370015A2B5 /* MotionModifier.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96E4095A1F24F7370015A2B5 /* MotionModifier.swift */; };
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-		96E409811F24F7370015A2B5 /* MotionTransitionState.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96E4095C1F24F7370015A2B5 /* MotionTransitionState.swift */; };
+		96E409811F24F7370015A2B5 /* MotionTargetState.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96E4095C1F24F7370015A2B5 /* MotionTargetState.swift */; };
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@@ -62,7 +70,6 @@
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-		96E4099A1F24F7570015A2B5 /* Motion.swift in Headers */ = {isa = PBXBuildFile; fileRef = 96E409501F24F7370015A2B5 /* Motion.swift */; settings = {ATTRIBUTES = (Public, ); }; };
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@@ -70,9 +77,9 @@
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@@ -82,15 +89,15 @@
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+		965FE9621FDCCE030098BDD0 /* MotionTransition+Complete.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MotionTransition+Complete.swift"; sourceTree = "<group>"; };
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-		965FE9661FDD99800098BDD0 /* Motion+Start.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Motion+Start.swift"; sourceTree = "<group>"; };
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-		965FE96E1FDEFA8B0098BDD0 /* Motion+Animate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Motion+Animate.swift"; sourceTree = "<group>"; };
+		965FE96E1FDEFA8B0098BDD0 /* MotionTransition+Animate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MotionTransition+Animate.swift"; sourceTree = "<group>"; };
 		965FE9761FE0976F0098BDD0 /* ConditionalPreprocessor.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ConditionalPreprocessor.swift; sourceTree = "<group>"; };
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@@ -107,7 +114,6 @@
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 		96E4094F1F24F7370015A2B5 /* Motion.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = Motion.h; sourceTree = "<group>"; };
-		96E409501F24F7370015A2B5 /* Motion.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Motion.swift; sourceTree = "<group>"; };
 		96E409511F24F7370015A2B5 /* MotionAnimation.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionAnimation.swift; sourceTree = "<group>"; };
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@@ -115,9 +121,9 @@
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-		96E4095A1F24F7370015A2B5 /* MotionTransition.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionTransition.swift; sourceTree = "<group>"; };
+		96E4095A1F24F7370015A2B5 /* MotionModifier.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionModifier.swift; sourceTree = "<group>"; };
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+		96E4095C1F24F7370015A2B5 /* MotionTargetState.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionTargetState.swift; sourceTree = "<group>"; };
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@@ -129,6 +135,17 @@
 /* End PBXFileReference section */
 /* Begin PBXGroup section */
+		965FE9781FE1D8120098BDD0 /* Transition */ = {
+			isa = PBXGroup;
+			children = (
+				965FE9791FE1D83D0098BDD0 /* MotionTransition.swift */,
+				965FE9661FDD99800098BDD0 /* MotionTransition+Start.swift */,
+				965FE96E1FDEFA8B0098BDD0 /* MotionTransition+Animate.swift */,
+				965FE9621FDCCE030098BDD0 /* MotionTransition+Complete.swift */,
+			);
+			path = Transition;
+			sourceTree = "<group>";
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@@ -151,12 +168,7 @@
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 				96E409BC1F24FC300015A2B5 /* LICENSE */,
 				96E4094F1F24F7370015A2B5 /* Motion.h */,
-				96E409501F24F7370015A2B5 /* Motion.swift */,
-				965FE9601FDCC3AF0098BDD0 /* MotionState.swift */,
 				965FE9681FDDA1F20098BDD0 /* MotionViewOrderStrategy.swift */,
-				965FE9661FDD99800098BDD0 /* Motion+Start.swift */,
-				965FE96E1FDEFA8B0098BDD0 /* Motion+Animate.swift */,
-				965FE9621FDCCE030098BDD0 /* Motion+Complete.swift */,
 				965FE9641FDCCE910098BDD0 /* MotionProgressRunner.swift */,
 				96E409511F24F7370015A2B5 /* MotionAnimation.swift */,
 				96E409521F24F7370015A2B5 /* MotionAnimationState.swift */,
@@ -165,12 +177,13 @@
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 				96E409581F24F7370015A2B5 /* MotionPlugin.swift */,
 				96E409591F24F7370015A2B5 /* MotionSnapshotType.swift */,
-				96E4095A1F24F7370015A2B5 /* MotionTransition.swift */,
+				96E4095A1F24F7370015A2B5 /* MotionModifier.swift */,
+				96E4095C1F24F7370015A2B5 /* MotionTargetState.swift */,
 				96E4095B1F24F7370015A2B5 /* MotionTransitionObserver.swift */,
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 				96E409431F24F7370015A2B5 /* Extensions */,
 				96E4095D1F24F7370015A2B5 /* Preprocessors */,
+				965FE9781FE1D8120098BDD0 /* Transition */,
 			);
 			path = Sources;
 			sourceTree = "<group>";
@@ -240,7 +253,6 @@
 				96E409951F24F7570015A2B5 /* Motion+UIView.swift in Headers */,
 				96E409961F24F7570015A2B5 /* Motion+UIViewController.swift in Headers */,
 				96E409971F24F7570015A2B5 /* MotionAnimationFillMode.swift in Headers */,
-				96E4099A1F24F7570015A2B5 /* Motion.swift in Headers */,
 				96E4099B1F24F7570015A2B5 /* MotionAnimation.swift in Headers */,
 				96E4099C1F24F7570015A2B5 /* MotionAnimationState.swift in Headers */,
 				96E4099D1F24F7570015A2B5 /* MotionCAAnimation.swift in Headers */,
@@ -248,9 +260,9 @@
 				96E409A01F24F7570015A2B5 /* MotionCoordinateSpace.swift in Headers */,
 				96E409A21F24F7570015A2B5 /* MotionPlugin.swift in Headers */,
 				96E409A31F24F7570015A2B5 /* MotionSnapshotType.swift in Headers */,
-				96E409A41F24F7570015A2B5 /* MotionTransition.swift in Headers */,
+				96E409A41F24F7570015A2B5 /* MotionModifier.swift in Headers */,
 				96E409A51F24F7570015A2B5 /* MotionTransitionObserver.swift in Headers */,
-				96E409A61F24F7570015A2B5 /* MotionTransitionState.swift in Headers */,
+				96E409A61F24F7570015A2B5 /* MotionTargetState.swift in Headers */,
 				96E409A71F24F7570015A2B5 /* CascadePreprocessor.swift in Headers */,
 				96E409A91F24F7570015A2B5 /* IgnoreSubviewModifiersPreprocessor.swift in Headers */,
 				96E409AA1F24F7570015A2B5 /* MatchPreprocessor.swift in Headers */,
@@ -258,6 +270,15 @@
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 				96E409AD1F24F7570015A2B5 /* TransitionPreprocessor.swift in Headers */,
 				96E409741F24F7370015A2B5 /* Motion.h in Headers */,
+				965FE9811FE304E70098BDD0 /* MotionViewOrderStrategy.swift in Headers */,
+				965FE9821FE304E70098BDD0 /* MotionProgressRunner.swift in Headers */,
+				965FE9831FE304E70098BDD0 /* MotionCoreAnimator.swift in Headers */,
+				965FE9841FE304E70098BDD0 /* MotionCorePreprocessor.swift in Headers */,
+				965FE9851FE304E70098BDD0 /* ConditionalPreprocessor.swift in Headers */,
+				965FE9861FE304E70098BDD0 /* MotionTransition.swift in Headers */,
+				965FE9881FE304E70098BDD0 /* MotionTransition+Start.swift in Headers */,
+				965FE9891FE304E70098BDD0 /* MotionTransition+Animate.swift in Headers */,
+				965FE98A1FE304E70098BDD0 /* MotionTransition+Complete.swift in Headers */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -321,7 +342,7 @@
 				96E409731F24F7370015A2B5 /* MotionAnimationFillMode.swift in Sources */,
 				96E409791F24F7370015A2B5 /* MotionContext.swift in Sources */,
 				965FE96B1FDDA4EA0098BDD0 /* MotionCorePreprocessor.swift in Sources */,
-				965FE9631FDCCE030098BDD0 /* Motion+Complete.swift in Sources */,
+				965FE9631FDCCE030098BDD0 /* MotionTransition+Complete.swift in Sources */,
 				96E4097D1F24F7370015A2B5 /* MotionPlugin.swift in Sources */,
 				965FE96D1FDDA6400098BDD0 /* MotionCoreAnimator.swift in Sources */,
 				96E4096E1F24F7370015A2B5 /* Motion+CG.swift in Sources */,
@@ -330,7 +351,7 @@
 				96E409821F24F7370015A2B5 /* CascadePreprocessor.swift in Sources */,
 				96E4096C1F24F7370015A2B5 /* Motion+CALayer.swift in Sources */,
 				96E409781F24F7370015A2B5 /* MotionCAAnimation.swift in Sources */,
-				96E409811F24F7370015A2B5 /* MotionTransitionState.swift in Sources */,
+				96E409811F24F7370015A2B5 /* MotionTargetState.swift in Sources */,
 				96E409801F24F7370015A2B5 /* MotionTransitionObserver.swift in Sources */,
 				96E409691F24F7370015A2B5 /* MotionTransitionAnimator.swift in Sources */,
 				96E409651F24F7370015A2B5 /* MotionAnimator.swift in Sources */,
@@ -343,19 +364,18 @@
 				96E409721F24F7370015A2B5 /* Motion+UIViewController.swift in Sources */,
 				96E4097E1F24F7370015A2B5 /* MotionSnapshotType.swift in Sources */,
 				965FE9691FDDA1F20098BDD0 /* MotionViewOrderStrategy.swift in Sources */,
+				965FE97A1FE1D83D0098BDD0 /* MotionTransition.swift in Sources */,
 				96E409871F24F7370015A2B5 /* SourcePreprocessor.swift in Sources */,
 				96E409701F24F7370015A2B5 /* Motion+UIKit.swift in Sources */,
 				965FE9771FE0976F0098BDD0 /* ConditionalPreprocessor.swift in Sources */,
 				96E4097B1F24F7370015A2B5 /* MotionCoordinateSpace.swift in Sources */,
 				96E409881F24F7370015A2B5 /* TransitionPreprocessor.swift in Sources */,
-				965FE9671FDD99800098BDD0 /* Motion+Start.swift in Sources */,
+				965FE9671FDD99800098BDD0 /* MotionTransition+Start.swift in Sources */,
 				96E4096A1F24F7370015A2B5 /* MotionViewPropertyViewContext.swift in Sources */,
 				96E409661F24F7370015A2B5 /* MotionAnimatorViewContext.swift in Sources */,
 				965FE9651FDCCE910098BDD0 /* MotionProgressRunner.swift in Sources */,
-				965FE9611FDCC3AF0098BDD0 /* MotionState.swift in Sources */,
+				96E4097F1F24F7370015A2B5 /* MotionModifier.swift in Sources */,
-				96E4097F1F24F7370015A2B5 /* MotionTransition.swift in Sources */,
+				965FE96F1FDEFA8B0098BDD0 /* MotionTransition+Animate.swift in Sources */,
-				965FE96F1FDEFA8B0098BDD0 /* Motion+Animate.swift in Sources */,
-				96E409751F24F7370015A2B5 /* Motion.swift in Sources */,
 				96E4096F1F24F7370015A2B5 /* Motion+Obj-C.swift in Sources */,
 				96E409711F24F7370015A2B5 /* Motion+UIView.swift in Sources */,
 			);

--- a/Sources/Animator/MotionAnimator.swift
+++ b/Sources/Animator/MotionAnimator.swift
@@ -30,7 +30,7 @@ import UIKit
 public protocol MotionAnimator: class {
    /// A reference to Motion.
-    weak var motion: Motion! { get set }
+    weak var motion: MotionTransition! { get set }
    /// Cleans the contexts.
    func clean()
@@ -68,8 +68,8 @@ public protocol MotionAnimator: class {
    /**
     Applies the given state to the given view.
-     - Parameter state: A MotionTransitionState.
+     - Parameter state: A MotionModifier.
     - Parameter to view: A UIView.
     */
-    func apply(state: MotionTransitionState, to view: UIView)
+    func apply(state: MotionTargetState, to view: UIView)
 }
--- a/Sources/Animator/MotionAnimatorViewContext.swift
+++ b/Sources/Animator/MotionAnimatorViewContext.swift
@@ -36,7 +36,7 @@ internal class MotionAnimatorViewContext {
    var snapshot: UIView
    /// The animation target state.
-    var targetState: MotionTransitionState
+    var targetState: MotionTargetState
    /// A boolean indicating if the view is appearing.
    var isAppearing: Bool
@@ -58,10 +58,10 @@ internal class MotionAnimatorViewContext {
     An initializer. 
     - Parameter animator: A MotionAnimator.
     - Parameter snapshot: A UIView.
-     - Parameter targetState: A MotionTransitionState.
+     - Parameter targetState: A MotionModifier.
     - Parameter isAppearing: A Boolean.
     */
-    required init(animator: MotionCoreAnimator, snapshot: UIView, targetState: MotionTransitionState, isAppearing: Bool) {
+    required init(animator: MotionCoreAnimator, snapshot: UIView, targetState: MotionTargetState, isAppearing: Bool) {
        self.animator = animator
        self.snapshot = snapshot
        self.targetState = targetState
@@ -77,11 +77,11 @@ internal class MotionAnimatorViewContext {
     A class function that determines if a view can be animated
     to a given state.
     - Parameter view: A UIView.
-     - Parameter state: A MotionTransitionState.
+     - Parameter state: A MotionModifier.
     - Parameter isAppearing: A boolean that determines whether the
     view is appearing.
     */
-    class func canAnimate(view: UIView, state: MotionTransitionState, isAppearing: Bool) -> Bool {
+    class func canAnimate(view: UIView, state: MotionTargetState, isAppearing: Bool) -> Bool {
        return false
    }
@@ -106,9 +106,9 @@ internal class MotionAnimatorViewContext {
    /**
     Applies the given state to the target state.
-     - Parameter state: A MotionTransitionState.
+     - Parameter state: A MotionModifier.
     */
-    func apply(state: MotionTransitionState) {}
+    func apply(state: MotionTargetState) {}
    /**
     Starts the animations with an appearing boolean flag.

--- a/Sources/Animator/MotionCoreAnimationViewContext.swift
+++ b/Sources/Animator/MotionCoreAnimationViewContext.swift
@@ -30,7 +30,7 @@ import UIKit
 internal class MotionCoreAnimationViewContext: MotionAnimatorViewContext {
    /// The transition states.
-    fileprivate var transitionStates = [String: (Any?, Any?)]()
+    fileprivate var state = [String: (Any?, Any?)]()
    /// A reference to the animation timing function.
    fileprivate var timingFunction = CAMediaTimingFunction.standard
@@ -51,7 +51,7 @@ internal class MotionCoreAnimationViewContext: MotionAnimatorViewContext {
        overlayLayer = nil
    }
-    override class func canAnimate(view: UIView, state: MotionTransitionState, isAppearing: Bool) -> Bool {
+    override class func canAnimate(view: UIView, state: MotionTargetState, isAppearing: Bool) -> Bool {
        return  nil != state.position           ||
                nil != state.size               ||
                nil != state.transform          ||
@@ -70,13 +70,13 @@ internal class MotionCoreAnimationViewContext: MotionAnimatorViewContext {
                       state.forceAnimate
    }
-    override func apply(state: MotionTransitionState) {
+    override func apply(state: MotionTargetState) {
        let targetState = viewState(targetState: state)
        for (key, targetValue) in targetState {
-            if nil == transitionStates[key] {
+            if nil == state[key] {
                let current = currentValue(for: key)
-                transitionStates[key] = (current, current)
+                state[key] = (current, current)
            }
            let oldAnimations = animations
@@ -87,8 +87,8 @@ internal class MotionCoreAnimationViewContext: MotionAnimatorViewContext {
    }
    override func resume(at elapsedTime: TimeInterval, isReversed: Bool) -> TimeInterval {
-        for (key, (fromValue, toValue)) in transitionStates {
+        for (key, (fromValue, toValue)) in state {
-            transitionStates[key] = (currentValue(for: key), isReversed ? fromValue : toValue)
+            state[key] = (currentValue(for: key), isReversed ? fromValue : toValue)
        }
        if isReversed {
@@ -125,28 +125,31 @@ internal class MotionCoreAnimationViewContext: MotionAnimatorViewContext {
    }
    override func startAnimations() -> TimeInterval {
-        if let beginState = targetState.beginState?.state {
+        if let beginStateModifiers = targetState.beginState {
+            let beginState = MotionTargetState(modifiers: beginStateModifiers)
            let appeared = viewState(targetState: beginState)
            for (k, v) in appeared {
                snapshot.layer.setValue(v, forKeyPath: k)
            }
-            if let (k, v) = beginState.overlay {
+            if let (color, opacity) = beginState.overlay {
                let overlay = getOverlayLayer()
-                overlay.backgroundColor = k
+                overlay.backgroundColor = color
-                overlay.opacity = Float(v)
+                overlay.opacity = Float(opacity)
            }
        }
        let disappeared = viewState(targetState: targetState)
-        for (k, v) in disappeared {
-            let isAppearingState = currentValue(for: k)
+        for (k, disappearedState) in disappeared {
-            let toValue = isAppearing ? isAppearingState : v
+            let appearingState = currentValue(for: k)
-            let fromValue = !isAppearing ? isAppearingState : v
+            let toValue = isAppearing ? appearingState : disappearedState
+            let fromValue = !isAppearing ? appearingState : disappearedState
-            transitionStates[k] = (fromValue, toValue)
+            state[k] = (fromValue, toValue)
        }
        return animate(delay: targetState.delay, duration: duration)
    }
 }
@@ -416,7 +419,7 @@ fileprivate extension MotionCoreAnimationViewContext {
        animations = []
-        for (key, (fromValue, toValue)) in transitionStates {
+        for (key, (fromValue, toValue)) in state {
            let neededTime = animate(key: key, beginTime: currentTime + delay, duration: duration, fromValue: fromValue, toValue: toValue)
            timeUntilStop = max(timeUntilStop, neededTime)
        }
@@ -426,10 +429,10 @@ fileprivate extension MotionCoreAnimationViewContext {
    /**
     Constructs a map of key paths to animation state values.
-     - Parameter targetState state: A MotionTransitionState.
+     - Parameter targetState state: A MotionModifier.
     - Returns: A map of key paths to animation values.
     */
-    func viewState(targetState ts: MotionTransitionState) -> [String: Any?] {
+    func viewState(targetState ts: MotionTargetState) -> [String: Any?] {
        var ts = ts
        var values = [String: Any?]()

--- a/Sources/Animator/MotionCoreAnimator.swift
+++ b/Sources/Animator/MotionCoreAnimator.swift
@@ -29,7 +29,7 @@
 import UIKit
 class MotionCoreAnimator: MotionAnimator {
-    weak public var motion: Motion!
+    weak public var motion: MotionTransition!
    /// A reference to the MotionContext.
    public var context: MotionContext! {
@@ -52,7 +52,7 @@ class MotionCoreAnimator: MotionAnimator {
        return 0
    }
-    func apply(state: MotionTransitionState, to view: UIView) {}
+    func apply(state: MotionTargetState, to view: UIView) {}
 }
--- a/Sources/Animator/MotionTransitionAnimator.swift
+++ b/Sources/Animator/MotionTransitionAnimator.swift
@@ -28,7 +28,7 @@
 import UIKit
-internal class MotionTransitionAnimator<T: MotionAnimatorViewContext>: MotionCoreAnimator {
+internal class MotionTargetStateAnimator<T: MotionAnimatorViewContext>: MotionCoreAnimator {
    /// An index of views to their corresponding animator context.
    var viewToContexts = [UIView: T]()
@@ -132,10 +132,10 @@ internal class MotionTransitionAnimator<T: MotionAnimatorViewContext>: MotionCor
    /**
     Applies the given state to the given view.
-     - Parameter state: A MotionTransitionState.
+     - Parameter state: A MotionModifier.
     - Parameter to view: A UIView.
     */
-    override func apply(state: MotionTransitionState, to view: UIView) {
+    override func apply(state: MotionTargetState, to view: UIView) {
        guard let v = viewToContexts[view] else {
            return
        }
@@ -144,7 +144,7 @@ internal class MotionTransitionAnimator<T: MotionAnimatorViewContext>: MotionCor
    }
 }
-fileprivate extension MotionTransitionAnimator {
+fileprivate extension MotionTargetStateAnimator {
    /**
     Creates a view context for a given view.
     - Parameter view: A UIView.

--- a/Sources/Animator/MotionViewPropertyViewContext.swift
+++ b/Sources/Animator/MotionViewPropertyViewContext.swift
@@ -39,7 +39,7 @@ internal class MotionViewPropertyViewContext: MotionAnimatorViewContext {
    /// Starting effect.
    fileprivate var startEffect: UIVisualEffect?
-    override class func canAnimate(view: UIView, state: MotionTransitionState, isAppearing: Bool) -> Bool {
+    override class func canAnimate(view: UIView, state: MotionTargetState, isAppearing: Bool) -> Bool {
        return view is UIVisualEffectView && nil != state.opacity
    }

--- a/Sources/Extensions/Motion+UIView.swift
+++ b/Sources/Extensions/Motion+UIView.swift
@@ -43,8 +43,8 @@ fileprivate struct AssociatedInstance {
    /// An optional reference to the motion animations.
    fileprivate var animations: [MotionAnimation]?
-    /// An optional reference to the motion transition animations.
+    /// An optional reference to the motion animation modifiers.
-    fileprivate var transitions: [MotionTransition]?
+    fileprivate var modifiers: [MotionModifier]?
    /// An alpha value.
    fileprivate var alpha: CGFloat?
@@ -55,7 +55,7 @@ fileprivate extension UIView {
    fileprivate var associatedInstance: AssociatedInstance {
        get {
            return AssociatedObject.get(base: self, key: &AssociatedInstanceKey) {
-                return AssociatedInstance(isEnabled: true, isEnabledForSubviews: true, identifier: nil, animations: nil, transitions: nil, alpha: 1)
+                return AssociatedInstance(isEnabled: true, isEnabledForSubviews: true, identifier: nil, animations: nil, modifiers: nil, alpha: 1)
            }
        }
        set(value) {
@@ -136,30 +136,30 @@ public extension UIView {
    }
    /**
-     A function that accepts a list of MotionTransition values.
+     A function that accepts a list of MotionTargetState values.
-     - Parameter transitions: A list of MotionTransition values.
+     - Parameter transitions: A list of MotionTargetState values.
     */
-    func transition(_ transitions: MotionTransition...) {
+    func transition(_ modifiers: MotionModifier...) {
-        transition(transitions)
+        transition(modifiers)
    }
    /**
-     A function that accepts an Array of MotionTransition values.
+     A function that accepts an Array of MotionTargetState values.
-     - Parameter transitions: An Array of MotionTransition values.
+     - Parameter transitions: An Array of MotionTargetState values.
     */
-    func transition(_ transitions: [MotionTransition]) {
+    func transition(_ modifiers: [MotionModifier]) {
-        motionTransitions = transitions
+        motionModifiers = modifiers
    }
 }
 internal extension UIView {
    /// The animations to run while in transition.
-    var motionTransitions: [MotionTransition]? {
+    var motionModifiers: [MotionModifier]? {
        get {
-            return associatedInstance.transitions
+            return associatedInstance.modifiers
        }
        set(value) {
-            associatedInstance.transitions = value
+            associatedInstance.modifiers = value
        }
    }
@@ -286,10 +286,10 @@ internal extension UIView {
    /**
     Calculates the optimized duration for a view.
-     - Parameter targetState: A MotionTransitionState.
+     - Parameter targetState: A MotionTargetState.
     - Returns: A TimeInterval.
     */
-    func optimizedDuration(targetState: MotionTransitionState) -> TimeInterval {
+    func optimizedDuration(targetState: MotionTargetState) -> TimeInterval {
        return optimizedDuration(position: targetState.position,
                                     size: targetState.size,
                                transform: targetState.transform)

--- a/Sources/Extensions/Motion+UIViewController.swift
+++ b/Sources/Extensions/Motion+UIViewController.swift
@@ -32,13 +32,13 @@ fileprivate var AssociatedInstanceKey: UInt8 = 0
 fileprivate struct AssociatedInstance {
    /// A reference to the modal animation.
-    var modalTransitionType: MotionTransitionType
+    var modalTransitionType: MotionTransitionAnimationType
    /// A reference to the navigation animation.
-    var navigationTransitionType: MotionTransitionType
+    var navigationTransitionType: MotionTransitionAnimationType
    /// A reference to the tabBar animation.
-    var tabBarTransitionType: MotionTransitionType
+    var tabBarTransitionType: MotionTransitionAnimationType
    /// A reference to the stored snapshot.
    var storedSnapshot: UIView?
@@ -75,7 +75,7 @@ extension UIViewController {
    }
    /// Default motion animation type for presenting & dismissing modally.
-    public var motionTransitionType: MotionTransitionType {
+    public var motionTransitionType: MotionTransitionAnimationType {
        get {
            return associatedInstance.modalTransitionType
        }
@@ -161,7 +161,7 @@ extension UIViewController {
 extension UINavigationController {
    /// Default motion animation type for push and pop within the navigation controller.
-    public var motionNavigationTransitionType: MotionTransitionType {
+    public var motionNavigationTransitionType: MotionTransitionAnimationType {
        get {
            return associatedInstance.navigationTransitionType
        }
@@ -173,7 +173,7 @@ extension UINavigationController {
 extension UITabBarController {
    /// Default motion animation type for switching tabs within the tab bar controller.
-    public var motionTabBarTransitionType: MotionTransitionType {
+    public var motionTabBarTransitionType: MotionTransitionAnimationType {
        get {
            return associatedInstance.tabBarTransitionType
        }

--- a/Sources/MotionContext.swift
+++ b/Sources/MotionContext.swift
@@ -45,7 +45,7 @@ public class MotionContext {
    internal var viewToAlphas = [UIView: CGFloat]()
    /// A reference of view to transition target state.
-    internal var viewToTargetState = [UIView: MotionTransitionState]()
+    internal var viewToTargetState = [UIView: MotionTargetState]()
    /// A reference of the superview to the subviews snapshots.
    internal var superviewToNoSnapshotSubviewMap = [UIView: [(Int, UIView)]]()
@@ -94,14 +94,21 @@ internal extension MotionContext {
        for v in views {
            v.layer.removeAllAnimations()
-            if container.convert(v.bounds, from: v).intersects(container.bounds) {
+            let targetState: MotionTargetState?
-                if let i = v.motionIdentifier {
-                    identifierMap[i] = v
+            if let modifiers = v.motionModifiers {
-                }
+                targetState = MotionTargetState(modifiers: modifiers)
-                if let i = v.motionTransitions {
+            } else {
-                    viewToTargetState[v] = MotionTransitionState(transitions: i)
+                targetState = nil
+            }
+            if true == targetState?.forceAnimate || container.convert(v.bounds, from: v).intersects(container.bounds) {
+                if let motionIdentifier = v.motionIdentifier {
+                    identifierMap[motionIdentifier] = v
                }
+                viewToTargetState[v] = targetState
            }
        }
    }
@@ -110,11 +117,11 @@ internal extension MotionContext {
 public extension MotionContext {
    /**
     A subscript that takes a given view and retrieves a
-     MotionTransitionState if one exists.
+     MotionModifier if one exists.
     - Parameter view: A UIView.
-     - Returns: An optional MotionTransitionState.
+     - Returns: An optional MotionTargetState.
     */
-    subscript(view: UIView) -> MotionTransitionState? {
+    subscript(view: UIView) -> MotionTargetState? {
        get {
            return viewToTargetState[view]
        }

--- a/Sources/MotionTransition.swift
+++ b/Sources/MotionTransition.swift
@@ -28,27 +28,27 @@
 import UIKit
-public class MotionTransition {
+public final class MotionModifier {
-    /// A reference to the callback that applies the MotionTransitionState.
+    /// A reference to the callback that applies the MotionModifier.
-    internal let apply: (inout MotionTransitionState) -> Void
+    internal let apply: (inout MotionTargetState) -> Void
    /**
     An initializer that accepts a given callback.
     - Parameter applyFunction: A given callback.
     */
-    init(applyFunction: @escaping (inout MotionTransitionState) -> Void) {
+    public init(applyFunction: @escaping (inout MotionTargetState) -> Void) {
        apply = applyFunction
    }
 }
-public extension MotionTransition {
+public extension MotionModifier {
    /**
     Animates the view with a matching motion identifier.
     - Parameter _ identifier: A String.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func motionIdentifier(_ identifier: String) -> MotionTransition {
+    static func motionIdentifier(_ identifier: String) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.motionIdentifier = identifier
        }
    }
@@ -58,10 +58,10 @@ public extension MotionTransition {
     given masksToBounds.
     - Parameter masksToBounds: A boolean value indicating the
     masksToBounds state.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func masksToBounds(_ masksToBounds: Bool) -> MotionTransition {
+    static func masksToBounds(_ masksToBounds: Bool) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.masksToBounds = masksToBounds
        }
    }
@@ -70,10 +70,10 @@ public extension MotionTransition {
     Animates the view's current background color to the
     given color.
     - Parameter color: A UIColor.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func background(color: UIColor) -> MotionTransition {
+    static func background(color: UIColor) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.backgroundColor = color.cgColor
        }
    }
@@ -82,10 +82,10 @@ public extension MotionTransition {
     Animates the view's current border color to the
     given color.
     - Parameter color: A UIColor.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func border(color: UIColor) -> MotionTransition {
+    static func border(color: UIColor) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.borderColor = color.cgColor
        }
    }
@@ -94,10 +94,10 @@ public extension MotionTransition {
     Animates the view's current border width to the
     given width.
     - Parameter width: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func border(width: CGFloat) -> MotionTransition {
+    static func border(width: CGFloat) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.borderWidth = width
        }
    }
@@ -106,10 +106,10 @@ public extension MotionTransition {
     Animates the view's current corner radius to the
     given radius.
     - Parameter radius: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func corner(radius: CGFloat) -> MotionTransition {
+    static func corner(radius: CGFloat) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.cornerRadius = radius
        }
    }
@@ -118,10 +118,10 @@ public extension MotionTransition {
     Animates the view's current transform (perspective, scale, rotate)
     to the given one.
     - Parameter _ transform: A CATransform3D.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func transform(_ transform: CATransform3D) -> MotionTransition {
+    static func transform(_ transform: CATransform3D) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.transform = transform
        }
    }
@@ -130,10 +130,10 @@ public extension MotionTransition {
     Animates the view's current perspective to the given one through
     a CATransform3D object.
     - Parameter _ perspective: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func perspective(_ perspective: CGFloat) -> MotionTransition {
+    static func perspective(_ perspective: CGFloat) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            var t = $0.transform ?? CATransform3DIdentity
            t.m34 = 1 / -perspective
            $0.transform = t
@@ -146,10 +146,10 @@ public extension MotionTransition {
     - Parameter x: A CGFloat.
     - Parameter y: A CGFloat.
     - Parameter z: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func rotate(x: CGFloat = 0, y: CGFloat = 0, z: CGFloat = 0) -> MotionTransition {
+    static func rotate(x: CGFloat = 0, y: CGFloat = 0, z: CGFloat = 0) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            var t = $0.transform ?? CATransform3DIdentity
            t = CATransform3DRotate(t, CGFloat(Double.pi) * x / 180, 1, 0, 0)
            t = CATransform3DRotate(t, CGFloat(Double.pi) * y / 180, 0, 1, 0)
@@ -161,18 +161,18 @@ public extension MotionTransition {
     Animates the view's current rotate to the given point.
     - Parameter _ point: A CGPoint.
     - Parameter z: A CGFloat, default is 0.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func rotate(_ point: CGPoint, z: CGFloat = 0) -> MotionTransition {
+    static func rotate(_ point: CGPoint, z: CGFloat = 0) -> MotionModifier {
        return .rotate(x: point.x, y: point.y, z: z)
    }
    /**
     Rotate 2d.
     - Parameter _ z: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func rotate(_ z: CGFloat) -> MotionTransition {
+    static func rotate(_ z: CGFloat) -> MotionModifier {
        return .rotate(z: z)
    }
@@ -181,10 +181,10 @@ public extension MotionTransition {
     - Parameter x: A CGFloat.
     - Parameter y: A CGFloat.
     - Parameter z: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func scale(x: CGFloat = 1, y: CGFloat = 1, z: CGFloat = 1) -> MotionTransition {
+    static func scale(x: CGFloat = 1, y: CGFloat = 1, z: CGFloat = 1) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.transform = CATransform3DScale($0.transform ?? CATransform3DIdentity, x, y, z)
        }
    }
@@ -192,9 +192,9 @@ public extension MotionTransition {
    /**
     Animates the view's current x & y scale to the given scale value.
     - Parameter _ xy: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func scale(_ xy: CGFloat) -> MotionTransition {
+    static func scale(_ xy: CGFloat) -> MotionModifier {
        return .scale(x: xy, y: xy)
    }
@@ -204,10 +204,10 @@ public extension MotionTransition {
     - Parameter x: A CGFloat.
     - Parameter y: A CGFloat.
     - Parameter z: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func translate(x: CGFloat = 0, y: CGFloat = 0, z: CGFloat = 0) -> MotionTransition {
+    static func translate(x: CGFloat = 0, y: CGFloat = 0, z: CGFloat = 0) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.transform = CATransform3DTranslate($0.transform ?? CATransform3DIdentity, x, y, z)
        }
    }
@@ -217,19 +217,19 @@ public extension MotionTransition {
     point value (x & y), and a z value.
     - Parameter _ point: A CGPoint.
     - Parameter z: A CGFloat, default is 0.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func translate(_ point: CGPoint, z: CGFloat = 0) -> MotionTransition {
+    static func translate(_ point: CGPoint, z: CGFloat = 0) -> MotionModifier {
        return .translate(x: point.x, y: point.y, z: z)
    }
    /**
     Animates the view's current position to the given point.
     - Parameter _ point: A CGPoint.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func position(_ point: CGPoint) -> MotionTransition {
+    static func position(_ point: CGPoint) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.position = point
        }
    }
@@ -238,30 +238,30 @@ public extension MotionTransition {
     Animates a view's current position to the given x and y values.
     - Parameter x: A CGloat.
     - Parameter y: A CGloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func position(x: CGFloat, y: CGFloat) -> MotionTransition {
+    static func position(x: CGFloat, y: CGFloat) -> MotionModifier {
        return .position(CGPoint(x: x, y: y))
    }
    /// Forces the view to not fade during a transition.
-    static var forceNonFade = MotionTransition {
+    static var forceNonFade = MotionModifier {
        $0.nonFade = true
    }
    /// Fades the view in during a transition.
-    static var fadeIn = MotionTransition.fade(1)
+    static var fadeIn = MotionModifier.fade(1)
    /// Fades the view out during a transition.
-    static var fadeOut = MotionTransition.fade(0)
+    static var fadeOut = MotionModifier.fade(0)
    /**
     Animates the view's current opacity to the given one.
     - Parameter to opacity: A Double.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func fade(_ opacity: Double) -> MotionTransition {
+    static func fade(_ opacity: Double) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.opacity = opacity
        }
    }
@@ -269,10 +269,10 @@ public extension MotionTransition {
    /**
     Animates the view's current zPosition to the given position.
     - Parameter _ position: An Int.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func zPosition(_ position: CGFloat) -> MotionTransition {
+    static func zPosition(_ position: CGFloat) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.zPosition = position
        }
    }
@@ -280,10 +280,10 @@ public extension MotionTransition {
    /**
     Animates the view's current size to the given one.
     - Parameter _ size: A CGSize.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func size(_ size: CGSize) -> MotionTransition {
+    static func size(_ size: CGSize) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.size = size
        }
    }
@@ -292,19 +292,19 @@ public extension MotionTransition {
     Animates the view's current size to the given width and height.
     - Parameter width: A CGFloat.
     - Parameter height: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func size(width: CGFloat, height: CGFloat) -> MotionTransition {
+    static func size(width: CGFloat, height: CGFloat) -> MotionModifier {
        return .size(CGSize(width: width, height: height))
    }
    /**
     Animates the view's current shadow path to the given one.
     - Parameter path: A CGPath.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func shadow(path: CGPath) -> MotionTransition {
+    static func shadow(path: CGPath) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.shadowPath = path
        }
    }
@@ -312,10 +312,10 @@ public extension MotionTransition {
    /**
     Animates the view's current shadow color to the given one.
     - Parameter color: A UIColor.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func shadow(color: UIColor) -> MotionTransition {
+    static func shadow(color: UIColor) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.shadowColor = color.cgColor
        }
    }
@@ -323,10 +323,10 @@ public extension MotionTransition {
    /**
     Animates the view's current shadow offset to the given one.
     - Parameter offset: A CGSize.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func shadow(offset: CGSize) -> MotionTransition {
+    static func shadow(offset: CGSize) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.shadowOffset = offset
        }
    }
@@ -334,10 +334,10 @@ public extension MotionTransition {
    /**
     Animates the view's current shadow opacity to the given one.
     - Parameter opacity: A Float.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func shadow(opacity: Float) -> MotionTransition {
+    static func shadow(opacity: Float) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.shadowOpacity = opacity
        }
    }
@@ -345,10 +345,10 @@ public extension MotionTransition {
    /**
     Animates the view's current shadow radius to the given one.
     - Parameter radius: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func shadow(radius: CGFloat) -> MotionTransition {
+    static func shadow(radius: CGFloat) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.shadowRadius = radius
        }
    }
@@ -356,10 +356,10 @@ public extension MotionTransition {
    /**
     Animates the view's contents rect to the given one.
     - Parameter rect: A CGRect.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func contents(rect: CGRect) -> MotionTransition {
+    static func contents(rect: CGRect) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.contentsRect = rect
        }
    }
@@ -367,10 +367,10 @@ public extension MotionTransition {
    /**
     Animates the view's contents scale to the given one.
     - Parameter scale: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func contents(scale: CGFloat) -> MotionTransition {
+    static func contents(scale: CGFloat) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.contentsScale = scale
        }
    }
@@ -378,10 +378,10 @@ public extension MotionTransition {
    /**
     The duration of the view's animation.
     - Parameter _ duration: A TimeInterval.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func duration(_ duration: TimeInterval) -> MotionTransition {
+    static func duration(_ duration: TimeInterval) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.duration = duration
        }
    }
@@ -390,15 +390,15 @@ public extension MotionTransition {
     Sets the view's animation duration to the longest
     running animation within a transition.
     */
-    static var preferredDurationMatchesLongest = MotionTransition.duration(.infinity)
+    static var preferredDurationMatchesLongest = MotionModifier.duration(.infinity)
    /**
     Delays the animation of a given view.
     - Parameter _ time: TimeInterval.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func delay(_ time: TimeInterval) -> MotionTransition {
+    static func delay(_ time: TimeInterval) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.delay = time
        }
    }
@@ -406,10 +406,10 @@ public extension MotionTransition {
    /**
     Sets the view's timing function for the transition.
     - Parameter _ timingFunction: A CAMediaTimingFunction.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func timingFunction(_ timingFunction: CAMediaTimingFunction) -> MotionTransition {
+    static func timingFunction(_ timingFunction: CAMediaTimingFunction) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.timingFunction = timingFunction
        }
    }
@@ -419,11 +419,11 @@ public extension MotionTransition {
     given a stiffness and damping.
     - Parameter stiffness: A CGFlloat.
     - Parameter damping: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
    @available(iOS 9, *)
-    static func spring(stiffness: CGFloat, damping: CGFloat) -> MotionTransition {
+    static func spring(stiffness: CGFloat, damping: CGFloat) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.spring = (stiffness, damping)
        }
    }
@@ -433,10 +433,10 @@ public extension MotionTransition {
     a curve in a downward direction, and a value of -1
     represents a curve in an upward direction.
     - Parameter intensity: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func arc(intensity: CGFloat = 1) -> MotionTransition {
+    static func arc(intensity: CGFloat = 1) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.arc = intensity
        }
    }
@@ -447,10 +447,10 @@ public extension MotionTransition {
     - Parameter direction: A CascadeDirection.
     - Parameter animationDelayedUntilMatchedViews: A boolean indicating whether
     or not to delay the subview animation until all have started.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func cascade(delta: TimeInterval = 0.02, direction: CascadeDirection = .topToBottom, animationDelayedUntilMatchedViews: Bool = false) -> MotionTransition {
+    static func cascade(delta: TimeInterval = 0.02, direction: CascadeDirection = .topToBottom, animationDelayedUntilMatchedViews: Bool = false) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.cascade = (delta, direction, animationDelayedUntilMatchedViews)
        }
    }
@@ -459,48 +459,108 @@ public extension MotionTransition {
     Creates an overlay on the animating view with a given color and opacity.
     - Parameter color: A UIColor.
     - Parameter opacity: A CGFloat.
-     - Returns: A MotionTransition.
+     - Returns: A MotionModifier.
     */
-    static func overlay(color: UIColor, opacity: CGFloat) -> MotionTransition {
+    static func overlay(color: UIColor, opacity: CGFloat) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.overlay = (color.cgColor, opacity)
        }
    }
 }
-public extension MotionTransition {
+// conditional modifiers
-    /**
+public extension MotionModifier {
-     Apply transitions directly to the view at the start of the transition.
+    /**
-     The transitions supplied here won't be animated.
+     Apply modifiers when the condition is true.
-     For source views, transitions are set directly at the begining of the animation.
+     - Parameter _ condition: A MotionConditionalContext.
-     For destination views, they replace the target state (final appearance).
+     - Returns: A Boolean.
     */
-    static func beginWith(transitions: [MotionTransition]) -> MotionTransition {
+    static func when(_ condition: @escaping (MotionConditionalContext) -> Bool, _ modifiers: [MotionModifier]) -> MotionModifier {
-        return MotionTransition {
-            if $0.beginState == nil {
+        return MotionModifier {
-                $0.beginState = MotionTransitionStateWrapper(state: [])
+            if nil == $0.conditionalModifiers {
+                $0.conditionalModifiers = []
            }
-            $0.beginState?.state.append(contentsOf: transitions)
+            $0.conditionalModifiers!.append((condition, modifiers))
        }
    }
+    static func when(_ condition: @escaping (MotionConditionalContext) -> Bool, _ modifiers: MotionModifier...) -> MotionModifier {
+        return .when(condition, modifiers)
+    }
    /**
-     Apply transitions directly to the view at the start of the transition if the view is 
+     Apply modifiers when matched.
-     matched with another view. The transitions supplied here won't be animated.
+     - Parameter _ modifiers: A list of modifiers.
+     - Returns: A MotionModifier.
+     */
+    static func whenMatched(_ modifiers: MotionModifier...) -> MotionModifier {
+        return .when({ $0.isMatched }, modifiers)
+    }
+    /**
+     Apply modifiers when presenting.
+     - Parameter _ modifiers: A list of modifiers.
+     - Returns: A MotionModifier.
+     */
+    static func whenPresenting(_ modifiers: MotionModifier...) -> MotionModifier {
+        return .when({ $0.isPresenting }, modifiers)
+    }
+    /**
+     Apply modifiers when dismissing.
+     - Parameter _ modifiers: A list of modifiers.
+     - Returns: A MotionModifier.
+     */
+    static func whenDismissing(_ modifiers: MotionModifier...) -> MotionModifier {
+        return .when({ !$0.isPresenting }, modifiers)
+    }
+    /**
+     Apply modifiers when appearingg.
+     - Parameter _ modifiers: A list of modifiers.
+     - Returns: A MotionModifier.
+     */
+    static func whenAppearing(_ modifiers: MotionModifier...) -> MotionModifier {
+        return .when({ $0.isAppearing }, modifiers)
+    }
+    /**
+     Apply modifiers when disappearing.
+     - Parameter _ modifiers: A list of modifiers.
+     - Returns: A MotionModifier.
+     */
+    static func whenDisappearing(_ modifiers: MotionModifier...) -> MotionModifier {
+        return .when({ !$0.isAppearing }, modifiers)
+    }
+}
+public extension MotionModifier {
+    /**
+     Apply transitions directly to the view at the start of the transition.
+     The transitions supplied here won't be animated.
     For source views, transitions are set directly at the begining of the animation.
     For destination views, they replace the target state (final appearance).
     */
-    static func beginWithIfMatched(transitions: [MotionTransition]) -> MotionTransition {
+    static func beginWith(_ modifiers: [MotionModifier]) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
-            if $0.beginStateIfMatched == nil {
+            if $0.beginState == nil {
-                $0.beginStateIfMatched = []
+                $0.beginState = []
            }
-            $0.beginStateIfMatched?.append(contentsOf: transitions)
+            $0.beginState?.append(contentsOf: modifiers)
        }
    }
+    static func beginWith(modifiers: [MotionModifier]) -> MotionModifier {
+        return .beginWith(modifiers)
+    }
+    static func beginWith(_ modifiers: MotionModifier...) -> MotionModifier {
+        return .beginWith(modifiers)
+    }
    /**
     Use global coordinate space.
@@ -511,20 +571,20 @@ public extension MotionTransition {
     When a view is matched, this is automatically enabled.
     The `source` transition will also enable this.
     */
-    static var useGlobalCoordinateSpace = MotionTransition {
+    static var useGlobalCoordinateSpace = MotionModifier {
        $0.coordinateSpace = .global
    }
    /// Ignore all motion transition attributes for a view's direct subviews.
-    static var ignoreSubviewTransitions: MotionTransition = .ignoreSubviewTransitions()
+    static var ignoreSubviewTransitions: MotionModifier = .ignoreSubviewTransitions()
    /**
     Ignore all motion transition attributes for a view's subviews.
     - Parameter recursive: If false, will only ignore direct subviews' transitions. 
     default false.
     */
-    static func ignoreSubviewTransitions(recursive: Bool = false) -> MotionTransition {
+    static func ignoreSubviewTransitions(recursive: Bool = false) -> MotionModifier {
-        return MotionTransition {
+        return MotionModifier {
            $0.ignoreSubviewTransitions = recursive
        }
    }
@@ -537,12 +597,12 @@ public extension MotionTransition {
     This transition actually does nothing by itself since .useOptimizedSnapshot is the default.
     */
-    static var useOptimizedSnapshot = MotionTransition {
+    static var useOptimizedSnapshot = MotionModifier {
        $0.snapshotType = .optimized
    }
    /// Create a snapshot using snapshotView(afterScreenUpdates:).
-    static var useNormalSnapshot = MotionTransition {
+    static var useNormalSnapshot = MotionModifier {
        $0.snapshotType = .normal
    }
@@ -551,7 +611,7 @@ public extension MotionTransition {
     This is slower than .useNormalSnapshot but gives more accurate snapshots for some views 
     (eg. UIStackView).
     */
-    static var useLayerRenderSnapshot = MotionTransition {
+    static var useLayerRenderSnapshot = MotionModifier {
        $0.snapshotType = .layerRender
    }
@@ -560,7 +620,7 @@ public extension MotionTransition {
     This will mess up the view hierarchy, therefore, view controllers have to rebuild
     their view structure after the transition finishes.
     */
-    static var useNoSnapshot = MotionTransition {
+    static var useNoSnapshot = MotionModifier {
        $0.snapshotType = .noSnapshot
    }
@@ -568,7 +628,7 @@ public extension MotionTransition {
     Force the view to animate (Motion will create animation contexts & snapshots for them, so 
     that they can be interactive).
     */
-    static var forceAnimate = MotionTransition {
+    static var forceAnimate = MotionModifier {
        $0.forceAnimate = true
    }
@@ -577,7 +637,7 @@ public extension MotionTransition {
     a .scale transition. This is to help Motion animate layers that doesn't support bounds animations.
     This also gives better performance.
     */
-    static var useScaleBasedSizeChange = MotionTransition {
+    static var useScaleBasedSizeChange = MotionModifier {
        $0.useScaleBasedSizeChange = true
    }
 }
--- a/Sources/MotionPlugin.swift
+++ b/Sources/MotionPlugin.swift
@@ -125,27 +125,32 @@ class MotionPlugin: MotionCorePreprocessor, MotionAnimator {
       - state: the target state to override
       - view: the view to override
   */
-  open func apply(state: MotionTransitionState, to view: UIView) {}
+  open func apply(state: MotionTargetState, to view: UIView) {}
 }
 // methods for enable/disable the current plugin
 extension MotionPlugin {
-  public static var isEnabled: Bool {
+    /// A boolean indicating whether plugins are available.
-    get {
+    public static var isEnabled: Bool {
-      return Motion.isEnabled(plugin: self)
+        get {
+            return MotionTransition.isEnabled(plugin: self)
+        }
+        set(value) {
+            if value {
+                enable()
+            } else {
+                disable()
+            }
+        }
    }
-    set {
-      if newValue {
+    /// Enable plugins.
-        enable()
+    public static func enable() {
-      } else {
+        MotionTransition.enable(plugin: self)
-        disable()
+    }
-      }
+    /// Disable plugins.
+    public static func disable() {
+        MotionTransition.disable(plugin: self)
    }
-  }
-  public static func enable() {
-    Motion.enable(plugin: self)
-  }
-  public static func disable() {
-    Motion.disable(plugin: self)
-  }
 }
--- a/Sources/MotionState.swift
+++ b/Sources/MotionState.swift
-/*
- * The MIT License (MIT)
- *
- * Copyright (C) 2017, Daniel Dahan and CosmicMind, Inc. <http://cosmicmind.com>.
- * All rights reserved.
- *
- * Original Inspiration & Author
- * Copyright (c) 2016 Luke Zhao <me@lkzhao.com>
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-@objc(MotionState)
-public enum MotionState: Int {
-    /// Motion is able to start a new transition.
-    case possible
-    /// UIKit has notified Motion about a pending transition.
-    /// Motion hasn't started preparation.
-    case notified
-    /// Motion's `start` method has been called. Preparing the animation.
-    case starting
-    /// Motions's `animate` method has been called. Animation has started.
-    case animating
-    /// Motions's `complete` method has been called. Transition has ended or has
-    /// been cancelled. Motion is cleaning up.
-    case completing
-}
--- a/Sources/MotionTransitionState.swift
+++ b/Sources/MotionTransitionState.swift
@@ -28,29 +28,12 @@
 import UIKit
-internal class MotionTransitionStateWrapper {
+public struct MotionTargetState {
-    /// A reference to a MotionTransitionState.
-    internal var state: MotionTransitionState
-    /**
-     An initializer that accepts a given MotionTransitionState.
-     - Parameter state: A MotionTransitionState.
-     */
-    internal init(state: MotionTransitionState) {
-        self.state = state
-    }
-}
-public struct MotionTransitionState {
    /// The initial state that the transition will start at.
-    internal var beginState: MotionTransitionStateWrapper?
+    internal var beginState: [MotionModifier]?
+    public var conditionalModifiers: [((MotionConditionalContext) -> Bool, [MotionModifier])]?
-    public var conditionalTransitions: [((MotionConditionalContext) -> Bool, [MotionTransition])]?
-    /// The start state if there is a match in the desition view controller.
-    public var beginStateIfMatched: [MotionTransition]?
    /// A reference to the position.
    public var position: CGPoint?
@@ -154,29 +137,29 @@ public struct MotionTransitionState {
    public var custom: [String: Any]?
    /**
-     An initializer that accepts an Array of MotionTransitions.
+     An initializer that accepts an Array of MotionTargetStates.
-     - Parameter transitions: An Array of MotionTransitions.
+     - Parameter transitions: An Array of MotionTargetStates.
     */
-    init(transitions: [MotionTransition]) {
+    init(modifiers: [MotionModifier]) {
-        append(contentsOf: transitions)
+        append(contentsOf: modifiers)
    }
 }
-extension MotionTransitionState {
+extension MotionTargetState {
    /**
-     Adds a MotionTransition to the current state.
+     Adds a MotionTargetState to the current state.
-     - Parameter _ element: A MotionTransition.
+     - Parameter _ modifier: A MotionTargetState.
     */
-    public mutating func append(_ element: MotionTransition) {
+    public mutating func append(_ modifier: MotionModifier) {
-        element.apply(&self)
+        modifier.apply(&self)
    }
    /**
-     Adds an Array of MotionTransitions to the current state.
+     Adds an Array of MotionTargetStates to the current state.
-     - Parameter contentsOf elements: An Array of MotionTransitions.
+     - Parameter contentsOf modifiers: An Array of MotionTargetStates.
     */
-    public mutating func append(contentsOf elements: [MotionTransition]) {
+    public mutating func append(contentsOf modifiers: [MotionModifier]) {
-        for v in elements {
+        for v in modifiers {
            v.apply(&self)
        }
    }
@@ -200,12 +183,12 @@ extension MotionTransitionState {
    }
 }
-extension MotionTransitionState: ExpressibleByArrayLiteral {
+extension MotionTargetState: ExpressibleByArrayLiteral {
    /**
     An initializer implementing the ExpressibleByArrayLiteral protocol.
-     - Parameter arrayLiteral elements: A list of MotionTransitions.
+     - Parameter arrayLiteral elements: A list of MotionTargetStates.
     */
-    public init(arrayLiteral elements: MotionTransition...) {
+    public init(arrayLiteral elements: MotionModifier...) {
        append(contentsOf: elements)
    }
 }
--- a/Sources/MotionTransitionObserver.swift
+++ b/Sources/MotionTransitionObserver.swift
@@ -28,11 +28,11 @@
 import Foundation
-public protocol MotionTransitionObserver {
+public protocol MotionTargetStateObserver {
    /**
     Executed when the elapsed time changes during a transition.
-     - Parameter transitionObserver: A MotionTransitionObserver. 
+     - Parameter transitionObserver: A MotionTargetStateObserver. 
     - Parameter didUpdateWith elapsedTime: A TimeInterval.
     */
-    func motion(transitionObserver: MotionTransitionObserver, didUpdateWith elapsedTime: TimeInterval)
+    func motion(transitionObserver: MotionTargetStateObserver, didUpdateWith elapsedTime: TimeInterval)
 }
--- a/Sources/Preprocessors/ConditionalPreprocessor.swift
+++ b/Sources/Preprocessors/ConditionalPreprocessor.swift
@@ -29,7 +29,7 @@
 import UIKit
 public struct MotionConditionalContext {
-    internal weak var motion: Motion!
+    internal weak var motion: MotionTransition!
    public weak var view: UIView!
    public private(set) var isAppearing: Bool
@@ -97,11 +97,11 @@ class ConditionalPreprocessor: MotionCorePreprocessor {
    func process(views: [UIView], isAppearing: Bool) {
        for v in views {
-            guard let conditionalTransitions = context[v]?.conditionalTransitions else {
+            guard let conditionalModifiers = context[v]?.conditionalModifiers else {
                continue
            }
-            for (condition, transitions) in conditionalTransitions {
+            for (condition, transitions) in conditionalModifiers {
                if condition(MotionConditionalContext(motion: motion, view: v, isAppearing: isAppearing)) {
                    context[v]!.append(contentsOf: transitions)
                }

--- a/Sources/Preprocessors/MatchPreprocessor.swift
+++ b/Sources/Preprocessors/MatchPreprocessor.swift
@@ -40,8 +40,8 @@ class MatchPreprocessor: MotionCorePreprocessor {
                continue
            }
-            var tvState = context[tv] ?? MotionTransitionState()
+            var tvState = context[tv] ?? MotionTargetState()
-            var fvState = context[fv] ?? MotionTransitionState()
+            var fvState = context[fv] ?? MotionTargetState()
            // match is just a two-way source effect
            tvState.motionIdentifier = motionIdentifier

--- a/Sources/Preprocessors/MotionCorePreprocessor.swift
+++ b/Sources/Preprocessors/MotionCorePreprocessor.swift
@@ -29,11 +29,11 @@
 import UIKit
 class MotionCorePreprocessor: MotionPreprocessor {
-    weak public var motion: Motion!
+    weak public var motion: MotionTransition!
    /// A reference to the MotionContext.
    public var context: MotionContext! {
-        return motion?.context
+        return motion!.context
    }
    func process(fromViews: [UIView], toViews: [UIView]) {}

--- a/Sources/Preprocessors/MotionPreprocessor.swift
+++ b/Sources/Preprocessors/MotionPreprocessor.swift
@@ -30,7 +30,7 @@ import UIKit
 public protocol MotionPreprocessor: class {
    /// A reference to Motion.
-    weak var motion: Motion! { get set }
+    weak var motion: MotionTransition! { get set }
    /**
     Processes the transitionary views.

--- a/Sources/Preprocessors/TransitionPreprocessor.swift
+++ b/Sources/Preprocessors/TransitionPreprocessor.swift
@@ -28,7 +28,7 @@
 import UIKit
-public enum MotionTransitionType {
+public enum MotionTransitionAnimationType {
    public enum Direction {
        case left
        case right
@@ -50,19 +50,19 @@ public enum MotionTransitionType {
    case zoom
    case zoomOut
-    indirect case selectBy(presenting: MotionTransitionType, dismissing: MotionTransitionType)
+    indirect case selectBy(presenting: MotionTransitionAnimationType, dismissing: MotionTransitionAnimationType)
    /**
     Sets the presenting and dismissing transitions.
-     - Parameter presenting: A MotionTransitionType.
+     - Parameter presenting: A MotionTransitionAnimationType.
-     - Returns: A MotionTransitionType.
+     - Returns: A MotionTransitionAnimationType.
    */
-    public static func autoReverse(presenting: MotionTransitionType) -> MotionTransitionType {
+    public static func autoReverse(presenting: MotionTransitionAnimationType) -> MotionTransitionAnimationType {
        return .selectBy(presenting: presenting, dismissing: presenting.reversed())
    }
    /// Returns a reversal transition.
-    func reversed() -> MotionTransitionType {
+    func reversed() -> MotionTransitionAnimationType {
        switch self {
        case .push(direction: .up):
            return .pull(direction: .down)
@@ -218,7 +218,9 @@ class TransitionPreprocessor: MotionCorePreprocessor {
        }
        if case .auto = defaultAnimation {
-            if animators.contains(where: { $0.canAnimate(view: tv, isAppearing: true) || $0.canAnimate(view: fv, isAppearing: false) }) {
+            if animators.contains(where: {
+                $0.canAnimate(view: tv, isAppearing: true) || $0.canAnimate(view: fv, isAppearing: false)
+            }) {
                defaultAnimation = .none
            } else if isNavigationController {
@@ -239,14 +241,16 @@ class TransitionPreprocessor: MotionCorePreprocessor {
        context[fv] = [.timingFunction(.standard), .duration(0.35)]
        context[tv] = [.timingFunction(.standard), .duration(0.35)]
-        let shadowState: [MotionTransition] = [.shadow(opacity: 0.5),
+        let shadowState: [MotionModifier] = [.shadow(opacity: 0.5),
-                                               .shadow(color: .black),
+                                             .shadow(color: .black),
-                                               .shadow(radius: 5),
+                                             .shadow(radius: 5),
-                                               .shadow(offset: .zero),
+                                             .shadow(offset: .zero),
-                                               .masksToBounds(false)]
+                                             .masksToBounds(false)]
        switch defaultAnimation {
        case .push(let direction):
+            context.insertToViewFirst = false
            context[tv]!.append(contentsOf: [.translate(shift(direction: direction, isAppearing: true)),
                                             .shadow(opacity: 0),
                                             .beginWith(transitions: shadowState),
@@ -277,6 +281,8 @@ class TransitionPreprocessor: MotionCorePreprocessor {
            context[tv]!.append(contentsOf: [.translate(shift(direction: direction, isAppearing: true)), .scale(0.8)])
        case .cover(let direction):
+            context.insertToViewFirst = false
            context[tv]!.append(contentsOf: [.translate(shift(direction: direction, isAppearing: true)),
                                             .shadow(opacity: 0),
                                             .beginWith(transitions: shadowState),
@@ -295,6 +301,8 @@ class TransitionPreprocessor: MotionCorePreprocessor {
            context[tv]!.append(contentsOf: [.overlay(color: .black, opacity: 0.1)])
        case .pageIn(let direction):
+            context.insertToViewFirst = false
            context[tv]!.append(contentsOf: [.translate(shift(direction: direction, isAppearing: true)),
                                             .shadow(opacity: 0),
                                             .beginWith(transitions: shadowState),
@@ -333,10 +341,13 @@ class TransitionPreprocessor: MotionCorePreprocessor {
        case .zoom:
            context.insertToViewFirst = true
            context[fv]!.append(contentsOf: [.scale(1.3), .fadeOut])
            context[tv]!.append(contentsOf: [.scale(0.7)])
        case .zoomOut:
+            context.insertToViewFirst = false
            context[tv]!.append(contentsOf: [.scale(1.3), .fadeOut])
            context[fv]!.append(contentsOf: [.scale(0.7)])
@@ -347,7 +358,7 @@ class TransitionPreprocessor: MotionCorePreprocessor {
    /**
     Shifts the transition by a given size.
-     - Parameter direction: A MotionTransitionType.Direction.
+     - Parameter direction: A MotionTransitionAnimationType.Direction.
     - Parameter isAppearing: A boolean indicating whether it is appearing
     or not.
     - Parameter size: An optional CGSize.
@@ -355,7 +366,7 @@ class TransitionPreprocessor: MotionCorePreprocessor {
     and `y` point for `x`.
     - Returns: A CGPoint.
     */
-    func shift(direction: MotionTransitionType.Direction, isAppearing: Bool, size: CGSize? = nil, transpose: Bool = false) -> CGPoint {
+    func shift(direction: MotionTransitionAnimationType.Direction, isAppearing: Bool, size: CGSize? = nil, transpose: Bool = false) -> CGPoint {
        let size = size ?? context.container.bounds.size
        let point: CGPoint

--- a/Sources/Motion+Animate.swift
+++ b/Sources/Motion+Animate.swift
@@ -28,7 +28,7 @@
 import UIKit
-extension Motion {
+extension MotionTransition {
    /// Starts the transition animation.
    func animate() {
        guard .starting == state else {
@@ -85,7 +85,6 @@ extension Motion {
                return animator.canAnimate(view: $0, isAppearing: true)
            })
-            print("T", t, "DURATION", duration)
            if .infinity == duration {
                animatorWantsInteractive = true
            } else {
@@ -95,12 +94,10 @@ extension Motion {
        totalDuration = t
-        print("T", t)
        if let forceFinishing = forceFinishing {
            complete(isFinishing: forceFinishing)
        } else if let startingProgress = startingProgress {
-           update(elapsedTime: startingProgress)
+           update(startingProgress)
        } else if animatorWantsInteractive {
            update(elapsedTime: 0)
        } else {

--- a/Sources/Motion+Complete.swift
+++ b/Sources/Motion+Complete.swift
@@ -28,7 +28,7 @@
 import UIKit
-extension Motion {
+extension MotionTransition {
    /**
     Complete the transition.
     - Parameter after: A TimeInterval.
@@ -36,7 +36,7 @@ extension Motion {
     has completed.
     */
    func complete(after: TimeInterval, isFinishing: Bool) {
-        guard [MotionState.animating, .starting, .notified].contains(state) else {
+        guard [MotionTransitionState.animating, .starting, .notified].contains(state) else {
            return
        }

--- a/Sources/Motion+Start.swift
+++ b/Sources/Motion+Start.swift
@@ -28,7 +28,7 @@
 import UIKit
-extension Motion {
+extension MotionTransition {
    /// Starts the transition animation.
    func start() {
        guard .notified == state else {
@@ -55,7 +55,7 @@ extension Motion {
    }
 }
-fileprivate extension Motion {
+fileprivate extension MotionTransition {
    /// Prepares the views frames.
    func prepareViewFrame() {
        guard let fv = fromView else {
@@ -119,10 +119,10 @@ fileprivate extension Motion {
    /// Prepares the animators.
    func prepareAnimators() {
-        animators.append(MotionTransitionAnimator<MotionCoreAnimationViewContext>())
+        animators.append(MotionTargetStateAnimator<MotionCoreAnimationViewContext>())
        if #available(iOS 10, tvOS 10, *) {
-            animators.append(MotionTransitionAnimator<MotionViewPropertyViewContext>())
+            animators.append(MotionTargetStateAnimator<MotionViewPropertyViewContext>())
        }
        for v in animators {
@@ -132,7 +132,7 @@ fileprivate extension Motion {
    /// Prepares the plugins.
    func preparePlugins() {
-        for x in Motion.enabledPlugins.map({
+        for x in MotionTransition.enabledPlugins.map({
            return $0.init()
        }) {
            plugins.append(x)
@@ -162,7 +162,7 @@ fileprivate extension Motion {
        container = UIView(frame: transitionContainer?.bounds ?? .zero)
        if !toOverFullScreen && !fromOverFullScreen {
-            updateContainerBackgroundColor()
+            container.backgroundColor = containerBackgroundColor
        }
        transitionContainer?.addSubview(container)
@@ -243,7 +243,7 @@ fileprivate extension Motion {
    }
 }
-fileprivate extension Motion {
+fileprivate extension MotionTransition {
    /// Executes the preprocessors' process function.
    func processPreprocessors() {
        for v in preprocessors {

--- a/Sources/Motion.swift
+++ b/Sources/Motion.swift
@@ -32,81 +32,81 @@ import UIKit
 public protocol MotionViewControllerDelegate {
    /**
     An optional delegation method that is executed motion will start the transition.
-     - Parameter motion: A Motion instance.
+     - Parameter motion: A MotionTransition instance.
     - Parameter willStartTransitionFrom viewController: A UIViewController.
     */
    @objc
-    optional func motionWillStartTransition(motion: Motion)
+    optional func motionWillStartTransition(motion: MotionTransition)
    /**
     An optional delegation method that is executed motion did end the transition.
-     - Parameter motion: A Motion instance.
+     - Parameter motion: A MotionTransition instance.
     - Parameter willStartTransitionFrom viewController: A UIViewController.
     */
    @objc
-    optional func motionDidEndTransition(motion: Motion)
+    optional func motionDidEndTransition(motion: MotionTransition)
    /**
     An optional delegation method that is executed motion did cancel the transition.
-     - Parameter motion: A Motion instance.
+     - Parameter motion: A MotionTransition instance.
     - Parameter willStartTransitionFrom viewController: A UIViewController.
     */
    @objc
-    optional func motionDidCancelTransition(motion: Motion)
+    optional func motionDidCancelTransition(motion: MotionTransition)
    /**
     An optional delegation method that is executed when the source
     view controller will start the transition.
-     - Parameter motion: A Motion instance.
+     - Parameter motion: A MotionTransition instance.
     - Parameter willStartTransitionFrom viewController: A UIViewController.
     */
    @objc
-    optional func motion(motion: Motion, willStartTransitionFrom viewController: UIViewController)
+    optional func motion(motion: MotionTransition, willStartTransitionFrom viewController: UIViewController)
    /**
     An optional delegation method that is executed when the source
     view controller did end the transition.
-     - Parameter motion: A Motion instance.
+     - Parameter motion: A MotionTransition instance.
     - Parameter willStartTransitionFrom viewController: A UIViewController.
     */
    @objc
-    optional func motion(motion: Motion, didEndTransitionFrom viewController: UIViewController)
+    optional func motion(motion: MotionTransition, didEndTransitionFrom viewController: UIViewController)
    /**
     An optional delegation method that is executed when the source
     view controller did cancel the transition.
-     - Parameter motion: A Motion instance.
+     - Parameter motion: A MotionTransition instance.
     - Parameter willStartTransitionFrom viewController: A UIViewController.
     */
    @objc
-    optional func motion(motion: Motion, didCancelTransitionFrom viewController: UIViewController)
+    optional func motion(motion: MotionTransition, didCancelTransitionFrom viewController: UIViewController)
    /**
     An optional delegation method that is executed when the destination
     view controller will start the transition.
-     - Parameter motion: A Motion instance.
+     - Parameter motion: A MotionTransition instance.
     - Parameter willStartTransitionFrom viewController: A UIViewController.
     */
    @objc
-    optional func motion(motion: Motion, willStartTransitionTo viewController: UIViewController)
+    optional func motion(motion: MotionTransition, willStartTransitionTo viewController: UIViewController)
    /**
     An optional delegation method that is executed when the destination
     view controller did end the transition.
-     - Parameter motion: A Motion instance.
+     - Parameter motion: A MotionTransition instance.
     - Parameter willStartTransitionFrom viewController: A UIViewController.
     */
    @objc
-    optional func motion(motion: Motion, didEndTransitionTo viewController: UIViewController)
+    optional func motion(motion: MotionTransition, didEndTransitionTo viewController: UIViewController)
    /**
     An optional delegation method that is executed when the destination
     view controller did cancel the transition.
-     - Parameter motion: A Motion instance.
+     - Parameter motion: A MotionTransition instance.
     - Parameter willStartTransitionFrom viewController: A UIViewController.
     */
    @objc
-    optional func motion(motion: Motion, didCancelTransitionTo viewController: UIViewController)
+    optional func motion(motion: MotionTransition, didCancelTransitionTo viewController: UIViewController)
 }
 /**
@@ -122,88 +122,142 @@ public protocol MotionViewControllerDelegate {
 func update(progress:Double)
 func end()
 func cancel()
- func apply(transitions: [MotionTransition], to view: UIView)
+ func apply(transitions: [MotionTargetState], to view: UIView)
 ```
 */
 import UIKit
-public class Motion: NSObject, MotionProgressRunnerDelegate {
+public class Motion: NSObject {
    /// Shared singleton object for controlling the transition
-    public static let shared = Motion()
+    public static let shared = MotionTransition()
+}
-    /// A boolean indicating if the user may interact with the
-    /// view controller while in transition.
+public typealias MotionCancelBlock = (Bool) -> Void
-    public var isUserInteractionEnabled = false
+extension Motion {
+    /**
+     Executes a block of code asynchronously on the main thread.
+     - Parameter execute: A block that is executed asynchronously on the main thread.
+     */
+    public class func async(_ execute: @escaping () -> Void) {
+        DispatchQueue.main.async(execute: execute)
+    }
-    /// A reference to the MotionViewOrderStrategy.
+    /**
-    public var viewOrderStrategy = MotionViewOrderStrategy.auto
+     Executes a block of code after a time delay.
+     - Parameter _ time: A delay time.
+     - Parameter execute: A block that is executed once delay has passed.
+     - Returns: An optional MotionCancelBlock.
+     */
+    @discardableResult
+    public class func delay(_ time: TimeInterval, execute: @escaping () -> Void) -> MotionCancelBlock? {
+        var cancelable: MotionCancelBlock?
+        let delayed: MotionCancelBlock = {
+            if !$0 {
+                async(execute)
+            }
+            cancelable = nil
+        }
+        cancelable = delayed
+        DispatchQueue.main.asyncAfter(deadline: .now() + time) {
+            cancelable?(false)
+        }
+        return cancelable
+    }
-    /// Plugins that are enabled during the transition.
+    /**
-    internal static var enabledPlugins = [MotionPlugin.Type]()
+     Cancels the delayed MotionCancelBlock.
+     - Parameter delayed completion: An MotionCancelBlock.
+     */
+    public class func cancel(delayed completion: MotionCancelBlock) {
+        completion(true)
+    }
-    /// A reference to a fullscreen snapshot.
+    /**
-    internal var fullScreenSnapshot: UIView!
+     Disables the default animations set on CALayers.
+     - Parameter animations: A callback that wraps the animations to disable.
+     */
+    public class func disable(_ animations: (() -> Void)) {
+        animate(duration: 0, animations: animations)
+    }
-    /// A reference to the MotionContext.
+    /**
-    public internal(set) var context: MotionContext!
+     Runs an animation with a specified duration.
+     - Parameter duration: An animation duration time.
+     - Parameter animations: An animation block.
+     - Parameter timingFunction: A CAMediaTimingFunction.
+     - Parameter completion: A completion block that is executed once
+     the animations have completed.
+     */
+    public class func animate(duration: CFTimeInterval, timingFunction: CAMediaTimingFunction = .easeInOut, animations: (() -> Void), completion: (() -> Void)? = nil) {
+        CATransaction.begin()
+        CATransaction.setAnimationDuration(duration)
+        CATransaction.setCompletionBlock(completion)
+        CATransaction.setAnimationTimingFunction(timingFunction)
+        animations()
+        CATransaction.commit()
+    }
-    /// A boolean indicating whether the transition interactive or not.
+    /**
-    public var isInteractive: Bool {
+     Creates a CAAnimationGroup.
-        return !progressRunner.isRunning
+     - Parameter animations: An Array of CAAnimation objects.
+     - Parameter timingFunction: A CAMediaTimingFunction.
+     - Parameter duration: An animation duration time for the group.
+     - Returns: A CAAnimationGroup.
+     */
+    public class func animate(group animations: [CAAnimation], timingFunction: CAMediaTimingFunction = .easeInOut, duration: CFTimeInterval = 0.5) -> CAAnimationGroup {
+        let group = CAAnimationGroup()
+        group.fillMode = MotionAnimationFillModeToValue(mode: .both)
+        group.isRemovedOnCompletion = false
+        group.animations = animations
+        group.duration = duration
+        group.timingFunction = timingFunction
+        return group
    }
+}
+public enum MotionTransitionState: Int {
+    /// Motion is able to start a new transition.
+    case possible
-    /// Source view controller.
+    /// UIKit has notified Motion about a pending transition.
-    public internal(set) var fromViewController: UIViewController?
+    /// Motion hasn't started preparation.
+    case notified
-    /// Destination view controller.
+    /// Motion's `start` method has been called. Preparing the animation.
-    public internal(set) var toViewController: UIViewController?
+    case starting
-    /// A reference to the fromView, fromViewController.view.
+    /// Motions's `animate` method has been called. Animation has started.
-    internal var fromView: UIView? {
+    case animating
-        return fromViewController?.view
-    }
-    /// A reference to the toView, toViewController.view.
+    /// Motions's `complete` method has been called. Transition has ended or has
-    internal var toView: UIView? {
+    /// been cancelled. Motion is cleaning up.
-        return toViewController?.view
+    case completing
-    }
+}
+open class MotionTransition: NSObject {
+    /// Default animation type.
+    internal var defaultAnimation = MotionTransitionAnimationType.auto
    /// The color of the transitioning container.
-    internal var containerBackgroundColor: UIColor?
+    internal var containerBackgroundColor = UIColor.black
-    /**
+    /// A boolean indicating if the user may interact with the
-     A UIViewControllerContextTransitioning object provided by UIKit, which
+    /// view controller while in transition.
-     might be nil when isTransitioning. This happens when calling motionReplaceViewController
+    public var isUserInteractionEnabled = false
-     */
-    internal weak var transitionContext: UIViewControllerContextTransitioning?
-    /// Progress of the current transition. 0 if no transition is happening.
+    /// A reference to the MotionViewOrderStrategy.
-    public internal(set) var elapsedTime: TimeInterval = 0 {
+    public var viewOrderStrategy = MotionViewOrderStrategy.auto
-        didSet {
-            guard .animating == state else {
-                return
-            }
-            updateTransitionObservers()
-            if isInteractive {
-                updateAnimators()
-            } else {
-                updatePlugins()
-            }
-            transitionContext?.updateInteractiveTransition(CGFloat(elapsedTime))
-        }
-    }
    /// State of the transition.
-    public internal(set) var state = MotionState.possible {
+    public internal(set) var state = MotionTransitionState.possible {
        didSet {
-            guard .notified != state else {
+            guard .notified != state, .starting != state else {
-                return
-            }
-            guard .starting != state else {
                return
            }
@@ -220,6 +274,11 @@ public class Motion: NSObject, MotionProgressRunnerDelegate {
    /// Whether or not we are presenting the destination view controller.
    public internal(set) var isPresenting = true
+    /// A boolean indicating whether the transition interactive or not.
+    public var isInteractive: Bool {
+        return !progressRunner.isRunning
+    }
    /**
     A view container used to hold all the animating views during a
     transition.
@@ -235,22 +294,6 @@ public class Motion: NSObject, MotionProgressRunnerDelegate {
    /// An optional completion callback.
    internal var completionCallback: ((Bool) -> Void)?
-    /// An Array of observers that are updated during a transition.
-    internal var transitionObservers: [MotionTransitionObserver]?
-    /// Max duration used by MotionAnimators and MotionPlugins.
-    public internal(set) var totalDuration: TimeInterval = 0
-    /// The currently running animation duration.
-    internal var currentAnimationDuration: TimeInterval = 0
-    /// A reference to a MotionProgressRunner.
-    lazy var progressRunner: MotionProgressRunner = {
-        let runner = MotionProgressRunner()
-        runner.delegate = self
-        return runner
-    }()
    /// A boolean indicating if the transition has finished.
    internal var isFinishing = true
@@ -267,8 +310,68 @@ public class Motion: NSObject, MotionProgressRunnerDelegate {
    internal var animatingFromViews = [UIView]()
    internal var animatingToViews = [UIView]()
-    /// Default animation type.
+    /// Plugins that are enabled during the transition.
-    internal var defaultAnimation = MotionTransitionType.auto
+    internal static var enabledPlugins = [MotionPlugin.Type]()
+    /// Source view controller.
+    public internal(set) var fromViewController: UIViewController?
+    /// A reference to the fromView, fromViewController.view.
+    internal var fromView: UIView? {
+        return fromViewController?.view
+    }
+    /// Destination view controller.
+    public internal(set) var toViewController: UIViewController?
+    /// A reference to the toView, toViewController.view.
+    internal var toView: UIView? {
+        return toViewController?.view
+    }
+    /// An Array of observers that are updated during a transition.
+    internal var transitionObservers: [MotionTargetStateObserver]?
+    /// Max duration used by MotionAnimators and MotionPlugins.
+    public internal(set) var totalDuration: TimeInterval = 0
+    /**
+     A UIViewControllerContextTransitioning object provided by UIKit, which
+     might be nil when isTransitioning. This happens when calling motionReplaceViewController
+     */
+    internal weak var transitionContext: UIViewControllerContextTransitioning?
+    /// A reference to the MotionContext.
+    public internal(set) var context: MotionContext!
+    /// A reference to a fullscreen snapshot.
+    internal var fullScreenSnapshot: UIView?
+    /// Progress of the current transition. 0 if no transition is happening.
+    public internal(set) var elapsedTime: TimeInterval = 0 {
+        didSet {
+            guard .animating == state else {
+                return
+            }
+            updateTransitionObservers()
+            if isInteractive {
+                updateAnimators()
+            } else {
+                updatePlugins()
+            }
+            transitionContext?.updateInteractiveTransition(CGFloat(elapsedTime))
+        }
+    }
+    /// A reference to a MotionProgressRunner.
+    lazy var progressRunner: MotionProgressRunner = {
+        let runner = MotionProgressRunner()
+        runner.delegate = self
+        return runner
+    }()
    /**
     By default, Motion will always appear to be interactive to UIKit. This forces it to appear non-interactive.
@@ -314,13 +417,19 @@ public class Motion: NSObject, MotionProgressRunnerDelegate {
    }
 }
-public extension Motion {
+extension MotionTransition: MotionProgressRunnerDelegate {
+    func update(elapsedTime: TimeInterval) {
+        self.elapsedTime = elapsedTime
+    }
+}
+extension MotionTransition {
    /**
     Receive callbacks on each animation frame.
     Observers will be cleaned when a transition completes.
-     - Parameter observer: A MotionTransitionObserver.
+     - Parameter observer: A MotionTargetStateObserver.
     */
-    func addTransitionObserver(observer: MotionTransitionObserver) {
+    func addTransitionObserver(observer: MotionTargetStateObserver) {
        if nil == transitionObservers {
            transitionObservers = []
        }
@@ -329,7 +438,7 @@ public extension Motion {
    }
 }
-private extension Motion {
+fileprivate extension MotionTransition {
    /// Updates the transition observers.
    func updateTransitionObservers() {
        guard let observers = transitionObservers else {
@@ -358,44 +467,19 @@ private extension Motion {
    }
 }
-public extension Motion {
+public extension MotionTransition {
    /**
     Updates the elapsed time for the interactive transition.
     - Parameter elapsedTime t: the current progress, must be between -1...1.
     */
-    public func update(elapsedTime: TimeInterval) {
+    public func update(_ percentageComplete: TimeInterval) {
        guard .animating == state else {
-            startingProgress = elapsedTime
+            startingProgress = percentageComplete
            return
        }
        progressRunner.stop()
-        self.elapsedTime = Double(CGFloat(elapsedTime).clamp(0, 1))
+        elapsedTime = Double(CGFloat(percentageComplete).clamp(0, 1))
-    }
-    /**
-     Finish the interactive transition.
-     Will stop the interactive transition and animate from the
-     current state to the **end** state
-     - Parameter isAnimated: A boolean indicating if the completion is animated.
-     */
-    public func end(isAnimated: Bool = true) {
-        guard isTransitioning else {
-            return
-        }
-        guard isAnimated else {
-            complete(isFinishing: true)
-            return
-        }
-        var t: TimeInterval = 0
-        for a in animators {
-            t = max(t, a.resume(at: elapsedTime * totalDuration, isReversed: false))
-        }
-        complete(after: t, isFinishing: true)
    }
    /**
@@ -436,36 +520,28 @@ public extension Motion {
     Motion.shared.apply([.position(x:50, y:50)], to: view)
     will set the view's position to 50, 50
-     - Parameter transitions: An Array of MotionTransitions.
+     - Parameter modifiers: An Array of MotionModifier.
     - Parameter to view: A UIView.
     */
-    public func apply(transitions: [MotionTransition], to view: UIView) {
+    public func apply(modifiers: [MotionModifier], to view: UIView) {
-        guard isTransitioning else {
+        guard .animating == state else {
            return
        }
-        let s = MotionTransitionState(transitions: transitions)
+        let targetState = MotionTargetState(modifiers: modifiers)
-        let v = context.pairedView(for: view) ?? view
+        if let otherView = context.pairedView(for: view) {
+            for animator in animators {
-        for a in animators {
+                animator.apply(state: targetState, to: otherView)
-            a.apply(state: s, to: v)
+            }
        }
-    }
-}
+        for animator in self.animators {
+            animator.apply(state: targetState, to: view)
-internal extension Motion {
-    /// Updates the container background color.
-    func updateContainerBackgroundColor() {
-        if let v = containerBackgroundColor {
-            container?.backgroundColor = v
-        } else if !toOverFullScreen && !fromOverFullScreen {
-            container?.backgroundColor = toView?.backgroundColor
        }
    }
 }
-internal extension Motion {
+internal extension MotionTransition {
    /**
     Checks if a given plugin is enabled.
     - Parameter plugin: A MotionPlugin.Type.
@@ -497,7 +573,7 @@ internal extension Motion {
    }
 }
-public extension Motion {
+public extension MotionTransition {
    /// Turn off built-in animations for the next transition.
    func disableDefaultAnimationForNextTransition() {
        defaultAnimation = .none
@@ -505,23 +581,23 @@ public extension Motion {
    /**
     Set the default animation for the next transition. This may override the
-     root-view's motionTransitions during the transition.
+     root-view's motionModifiers during the transition.
-     - Parameter animation: A MotionTransitionType.
+     - Parameter animation: A MotionTransitionAnimationType.
     */
-    func setAnimationForNextTransition(_ animation: MotionTransitionType) {
+    func setAnimationForNextTransition(_ animation: MotionTransitionAnimationType) {
        defaultAnimation = animation
    }
    /**
     Set the container background color for the next transition.
-     - Parameter _ color: An optional UIColor.
+     - Parameter _ color: A UIColor.
     */
-    func setContainerBackgroundColorForNextTransition(_ color: UIColor?) {
+    func setContainerBackgroundColorForNextTransition(_ color: UIColor) {
        containerBackgroundColor = color
    }
 }
-public extension Motion {
+public extension MotionTransition {
    /**
     A helper transition function.
     - Parameter from: A UIViewController.
@@ -545,7 +621,7 @@ public extension Motion {
    }
 }
-internal extension Motion {
+internal extension MotionTransition {
    /**
     Processes the start transition delegation methods.
     - Parameter fromViewController: An optional UIViewController.
@@ -661,7 +737,7 @@ internal extension Motion {
    }
 }
-internal extension Motion {
+internal extension MotionTransition {
    /**
     Helper for processing the MotionViewControllerDelegate.
     - Parameter viewController: A UIViewController of type `T`.
@@ -684,7 +760,7 @@ internal extension Motion {
    }
 }
-extension Motion: UIViewControllerAnimatedTransitioning {
+extension MotionTransition: UIViewControllerAnimatedTransitioning {
    /**
     The animation method that is used to coordinate the transition.
     - Parameter using transitionContext: A UIViewControllerContextTransitioning.
@@ -716,7 +792,7 @@ extension Motion: UIViewControllerAnimatedTransitioning {
    }
 }
-extension Motion: UIViewControllerTransitioningDelegate {
+extension MotionTransition: UIViewControllerTransitioningDelegate {
    /// A reference to the interactive transitioning instance.
    var interactiveTransitioning: UIViewControllerInteractiveTransitioning? {
        return forceNonInteractive ? nil : self
@@ -755,7 +831,7 @@ extension Motion: UIViewControllerTransitioningDelegate {
    }
 }
-extension Motion: UIViewControllerInteractiveTransitioning {
+extension MotionTransition: UIViewControllerInteractiveTransitioning {
    public var wantsInteractiveStart: Bool {
        return true
    }
@@ -765,7 +841,7 @@ extension Motion: UIViewControllerInteractiveTransitioning {
    }
 }
-extension Motion: UINavigationControllerDelegate {
+extension MotionTransition: UINavigationControllerDelegate {
    public func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationControllerOperation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        guard !isTransitioning else {
            return nil
@@ -785,7 +861,7 @@ extension Motion: UINavigationControllerDelegate {
    }
 }
-extension Motion: UITabBarControllerDelegate {
+extension MotionTransition: UITabBarControllerDelegate {
    public func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
        if isTransitioning {
            cancel(isAnimated: false)
@@ -817,91 +893,3 @@ extension Motion: UITabBarControllerDelegate {
    }
 }
-public typealias MotionCancelBlock = (Bool) -> Void
-extension Motion {
-    /**
-     Executes a block of code asynchronously on the main thread.
-     - Parameter execute: A block that is executed asynchronously on the main thread.
-     */
-    public class func async(_ execute: @escaping () -> Void) {
-        DispatchQueue.main.async(execute: execute)
-    }
-    /**
-     Executes a block of code after a time delay.
-     - Parameter _ time: A delay time.
-     - Parameter execute: A block that is executed once delay has passed.
-     - Returns: An optional MotionCancelBlock.
-     */
-    @discardableResult
-    public class func delay(_ time: TimeInterval, execute: @escaping () -> Void) -> MotionCancelBlock? {
-        var cancelable: MotionCancelBlock?
-        let delayed: MotionCancelBlock = {
-            if !$0 {
-                async(execute)
-            }
-            cancelable = nil
-        }
-        cancelable = delayed
-        DispatchQueue.main.asyncAfter(deadline: .now() + time) {
-            cancelable?(false)
-        }
-        return cancelable
-    }
-    /**
-     Cancels the delayed MotionCancelBlock.
-     - Parameter delayed completion: An MotionCancelBlock.
-     */
-    public class func cancel(delayed completion: MotionCancelBlock) {
-        completion(true)
-    }
-    /**
-     Disables the default animations set on CALayers.
-     - Parameter animations: A callback that wraps the animations to disable.
-     */
-    public class func disable(_ animations: (() -> Void)) {
-        animate(duration: 0, animations: animations)
-    }
-    /**
-     Runs an animation with a specified duration.
-     - Parameter duration: An animation duration time.
-     - Parameter animations: An animation block.
-     - Parameter timingFunction: A CAMediaTimingFunction.
-     - Parameter completion: A completion block that is executed once
-     the animations have completed.
-     */
-    public class func animate(duration: CFTimeInterval, timingFunction: CAMediaTimingFunction = .easeInOut, animations: (() -> Void), completion: (() -> Void)? = nil) {
-        CATransaction.begin()
-        CATransaction.setAnimationDuration(duration)
-        CATransaction.setCompletionBlock(completion)
-        CATransaction.setAnimationTimingFunction(timingFunction)
-        animations()
-        CATransaction.commit()
-    }
-    /**
-     Creates a CAAnimationGroup.
-     - Parameter animations: An Array of CAAnimation objects.
-     - Parameter timingFunction: A CAMediaTimingFunction.
-     - Parameter duration: An animation duration time for the group.
-     - Returns: A CAAnimationGroup.
-     */
-    public class func animate(group animations: [CAAnimation], timingFunction: CAMediaTimingFunction = .easeInOut, duration: CFTimeInterval = 0.5) -> CAAnimationGroup {
-        let group = CAAnimationGroup()
-        group.fillMode = MotionAnimationFillModeToValue(mode: .both)
-        group.isRemovedOnCompletion = false
-        group.animations = animations
-        group.duration = duration
-        group.timingFunction = timingFunction
-        return group
-    }
-}