updated MotionTransition extensions before full review

104aead0 · Daniel Dahan · 150344a1 · 104aead0 · 104aead0 · 104aead0
Commit 104aead0 authored Dec 15, 2017 by Daniel Dahan
16 changed files
--- a/Motion.xcodeproj/project.pbxproj
+++ b/Motion.xcodeproj/project.pbxproj
@@ -28,6 +28,8 @@
 		965FE98D1FE334E10098BDD0 /* MotionTransition+UIViewControllerTransitioningDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 965FE98C1FE334E10098BDD0 /* MotionTransition+UIViewControllerTransitioningDelegate.swift */; };
 		965FE9911FE43DA60098BDD0 /* MotionTransition+UITabBarControllerDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 965FE9901FE43DA60098BDD0 /* MotionTransition+UITabBarControllerDelegate.swift */; };
 		965FE9931FE43DE10098BDD0 /* MotionTransition+UINavigationControllerDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 965FE9921FE43DE10098BDD0 /* MotionTransition+UINavigationControllerDelegate.swift */; };
+		965FE9A11FE43EF80098BDD0 /* MotionTransition+CustomTransition.swift in Sources */ = {isa = PBXBuildFile; fileRef = 965FE9A01FE43EF80098BDD0 /* MotionTransition+CustomTransition.swift */; };
+		965FE9A31FE4407D0098BDD0 /* MotionTransition+Interactive.swift in Sources */ = {isa = PBXBuildFile; fileRef = 965FE9A21FE4407D0098BDD0 /* MotionTransition+Interactive.swift */; };
 		96E409651F24F7370015A2B5 /* MotionAnimator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96E4093D1F24F7370015A2B5 /* MotionAnimator.swift */; };
 		96E409661F24F7370015A2B5 /* MotionAnimatorViewContext.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96E4093E1F24F7370015A2B5 /* MotionAnimatorViewContext.swift */; };
 		96E409671F24F7370015A2B5 /* MotionCoreAnimationViewContext.swift in Sources */ = {isa = PBXBuildFile; fileRef = 96E4093F1F24F7370015A2B5 /* MotionCoreAnimationViewContext.swift */; };
@@ -104,6 +106,8 @@
 		965FE98C1FE334E10098BDD0 /* MotionTransition+UIViewControllerTransitioningDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MotionTransition+UIViewControllerTransitioningDelegate.swift"; sourceTree = "<group>"; };
 		965FE9901FE43DA60098BDD0 /* MotionTransition+UITabBarControllerDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MotionTransition+UITabBarControllerDelegate.swift"; sourceTree = "<group>"; };
 		965FE9921FE43DE10098BDD0 /* MotionTransition+UINavigationControllerDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MotionTransition+UINavigationControllerDelegate.swift"; sourceTree = "<group>"; };
+		965FE9A01FE43EF80098BDD0 /* MotionTransition+CustomTransition.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MotionTransition+CustomTransition.swift"; sourceTree = "<group>"; };
+		965FE9A21FE4407D0098BDD0 /* MotionTransition+Interactive.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MotionTransition+Interactive.swift"; sourceTree = "<group>"; };
 		96C98DD11E424AB000B22906 /* Motion.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Motion.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		96E4093D1F24F7370015A2B5 /* MotionAnimator.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionAnimator.swift; sourceTree = "<group>"; };
 		96E4093E1F24F7370015A2B5 /* MotionAnimatorViewContext.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MotionAnimatorViewContext.swift; sourceTree = "<group>"; };
@@ -151,6 +155,8 @@
 				965FE98C1FE334E10098BDD0 /* MotionTransition+UIViewControllerTransitioningDelegate.swift */,
 				965FE9901FE43DA60098BDD0 /* MotionTransition+UITabBarControllerDelegate.swift */,
 				965FE9921FE43DE10098BDD0 /* MotionTransition+UINavigationControllerDelegate.swift */,
+				965FE9A01FE43EF80098BDD0 /* MotionTransition+CustomTransition.swift */,
+				965FE9A21FE4407D0098BDD0 /* MotionTransition+Interactive.swift */,
 			);
 			path = Transition;
 			sourceTree = "<group>";
@@ -371,6 +377,7 @@
 				96E409841F24F7370015A2B5 /* IgnoreSubviewModifiersPreprocessor.swift in Sources */,
 				96E409771F24F7370015A2B5 /* MotionAnimationState.swift in Sources */,
 				96E409761F24F7370015A2B5 /* MotionAnimation.swift in Sources */,
+				965FE9A31FE4407D0098BDD0 /* MotionTransition+Interactive.swift in Sources */,
 				96E4096B1F24F7370015A2B5 /* Motion+Array.swift in Sources */,
 				96E409721F24F7370015A2B5 /* Motion+UIViewController.swift in Sources */,
 				96E4097E1F24F7370015A2B5 /* MotionSnapshotType.swift in Sources */,
@@ -378,6 +385,7 @@
 				965FE97A1FE1D83D0098BDD0 /* MotionTransition.swift in Sources */,
 				965FE98D1FE334E10098BDD0 /* MotionTransition+UIViewControllerTransitioningDelegate.swift in Sources */,
 				96E409871F24F7370015A2B5 /* SourcePreprocessor.swift in Sources */,
+				965FE9A11FE43EF80098BDD0 /* MotionTransition+CustomTransition.swift in Sources */,
 				96E409701F24F7370015A2B5 /* Motion+UIKit.swift in Sources */,
 				965FE9771FE0976F0098BDD0 /* ConditionalPreprocessor.swift in Sources */,
 				96E4097B1F24F7370015A2B5 /* MotionCoordinateSpace.swift in Sources */,

--- a/Sources/Animator/MotionAnimator.swift
+++ b/Sources/Animator/MotionAnimator.swift
@@ -53,18 +53,18 @@ public protocol MotionAnimator: class {
    /**
     Moves the view's animation to the given elapsed time.
-     - Parameter to elapsedTime: A TimeInterval.
+     - Parameter to progress: A TimeInterval.
     */
-    func seek(to elapsedTime: TimeInterval)
+    func seek(to progress: TimeInterval)
    /**
     Resumes the animation with a given elapsed time and
     optional reversed boolean.
-     - Parameter at elapsedTime: A TimeInterval.
+     - Parameter at progress: A TimeInterval.
     - Parameter isReversed: A boolean to reverse the animation
     or not.
     */
-    func resume(at elapsedTime: TimeInterval, isReversed: Bool) -> TimeInterval
+    func resume(at progress: TimeInterval, isReversed: Bool) -> TimeInterval
    /**
     Applies the given state to the given view.

--- a/Sources/Animator/MotionAnimatorViewContext.swift
+++ b/Sources/Animator/MotionAnimatorViewContext.swift
@@ -88,21 +88,21 @@ internal class MotionAnimatorViewContext {
    /**
     Resumes the animation with a given elapsed time and
     optional reversed boolean.
-     - Parameter at elapsedTime: A TimeInterval.
+     - Parameter at progress: A TimeInterval.
     - Parameter isReversed: A boolean to reverse the animation 
     or not.
     - Returns: A TimeInterval.
     */
    @discardableResult
-    func resume(at elapsedTime: TimeInterval, isReversed: Bool) -> TimeInterval {
+    func resume(at progress: TimeInterval, isReversed: Bool) -> TimeInterval {
        return 0
    }
    /**
     Moves the animation to the given elapsed time.
-     - Parameter to elapsedTime: A TimeInterval.
+     - Parameter to progress: A TimeInterval.
     */
-    func seek(to elapsedTime: TimeInterval) {}
+    func seek(to progress: TimeInterval) {}
    /**
     Applies the given state to the target state.

--- a/Sources/Animator/MotionCoreAnimationViewContext.swift
+++ b/Sources/Animator/MotionCoreAnimationViewContext.swift
@@ -86,26 +86,26 @@ internal class MotionCoreAnimationViewContext: MotionAnimatorViewContext {
        }
    }
-    override func resume(at elapsedTime: TimeInterval, isReversed: Bool) -> TimeInterval {
+    override func resume(at progress: TimeInterval, isReversed: Bool) -> TimeInterval {
        for (key, (fromValue, toValue)) in state {
            state[key] = (currentValue(for: key), isReversed ? fromValue : toValue)
        }
        if isReversed {
-            if elapsedTime > targetState.delay + duration {
+            if progress > targetState.delay + duration {
-                let backDelay = elapsedTime - (targetState.delay + duration)
+                let backDelay = progress - (targetState.delay + duration)
                return animate(delay: backDelay, duration: duration)
-            } else if elapsedTime > targetState.delay {
+            } else if progress > targetState.delay {
-                return animate(delay: 0, duration: duration - elapsedTime - targetState.delay)
+                return animate(delay: 0, duration: duration - progress - targetState.delay)
            }
        } else {
-            if elapsedTime <= targetState.delay {
+            if progress <= targetState.delay {
-                return animate(delay: targetState.delay - elapsedTime, duration: duration)
+                return animate(delay: targetState.delay - progress, duration: duration)
-            } else if elapsedTime <= targetState.delay + duration {
+            } else if progress <= targetState.delay + duration {
-                let timePassedDelay = elapsedTime - targetState.delay
+                let timePassedDelay = progress - targetState.delay
                return animate(delay: 0, duration: duration - timePassedDelay)
            }
        }
@@ -113,8 +113,8 @@ internal class MotionCoreAnimationViewContext: MotionAnimatorViewContext {
        return 0
    }
-    override func seek(to elapsedTime: TimeInterval) {
+    override func seek(to progress: TimeInterval) {
-        let timeOffset = CGFloat(elapsedTime - targetState.delay)
+        let timeOffset = CGFloat(progress - targetState.delay)
        for (layer, key, anim) in animations {
            anim.speed = 0

--- a/Sources/Animator/MotionCoreAnimator.swift
+++ b/Sources/Animator/MotionCoreAnimator.swift
@@ -46,9 +46,9 @@ class MotionCoreAnimator: MotionAnimator {
        return 0
    }
-    func seek(to elapsedTime: TimeInterval) {}
+    func seek(to progress: TimeInterval) {}
-    func resume(at elapsedTime: TimeInterval, isReversed: Bool) -> TimeInterval {
+    func resume(at progress: TimeInterval, isReversed: Bool) -> TimeInterval {
        return 0
    }

--- a/Sources/Animator/MotionTransitionAnimator.swift
+++ b/Sources/Animator/MotionTransitionAnimator.swift
@@ -101,30 +101,30 @@ internal class MotionTargetStateAnimator<T: MotionAnimatorViewContext>: MotionCo
    /**
     Moves the view's animation to the given elapsed time.
-     - Parameter to elapsedTime: A TimeInterval.
+     - Parameter to progress: A TimeInterval.
     */
-    override func seek(to elapsedTime: TimeInterval) {
+    override func seek(to progress: TimeInterval) {
        for v in viewToContexts.values {
-            v.seek(to: elapsedTime)
+            v.seek(to: progress)
        }
    }
    /**
     Resumes the animation with a given elapsed time and
     optional reversed boolean.
-     - Parameter at elapsedTime: A TimeInterval.
+     - Parameter at progress: A TimeInterval.
     - Parameter isReversed: A boolean to reverse the animation
     or not.
     */
-    override func resume(at elapsedTime: TimeInterval, isReversed: Bool) -> TimeInterval {
+    override func resume(at progress: TimeInterval, isReversed: Bool) -> TimeInterval {
        var duration: TimeInterval = 0
        for (_, v) in viewToContexts {
            if nil == v.targetState.duration {
-                v.duration = max(v.duration, v.snapshot.optimizedDuration(targetState: v.targetState) + elapsedTime)
+                v.duration = max(v.duration, v.snapshot.optimizedDuration(targetState: v.targetState) + progress)
            }
-            duration = max(duration, v.resume(at: elapsedTime, isReversed: isReversed))
+            duration = max(duration, v.resume(at: progress, isReversed: isReversed))
        }
        return duration

--- a/Sources/Animator/MotionViewPropertyViewContext.swift
+++ b/Sources/Animator/MotionViewPropertyViewContext.swift
@@ -43,7 +43,7 @@ internal class MotionViewPropertyViewContext: MotionAnimatorViewContext {
        return view is UIVisualEffectView && nil != state.opacity
    }
-    override func resume(at elapsedTime: TimeInterval, isReversed: Bool) -> TimeInterval {
+    override func resume(at progress: TimeInterval, isReversed: Bool) -> TimeInterval {
        guard let visualEffectView = snapshot as? UIVisualEffectView else {
            return 0
        }
@@ -65,9 +65,9 @@ internal class MotionViewPropertyViewContext: MotionAnimatorViewContext {
        return duration
    }
-    override func seek(to elapsedTime: TimeInterval) {
+    override func seek(to progress: TimeInterval) {
        viewPropertyAnimator?.pauseAnimation()
-        viewPropertyAnimator?.fractionComplete = CGFloat(elapsedTime / duration)
+        viewPropertyAnimator?.fractionComplete = CGFloat(progress / duration)
    }
    override func clean() {

--- a/Sources/MotionPlugin.swift
+++ b/Sources/MotionPlugin.swift
@@ -101,9 +101,9 @@ class MotionPlugin: MotionCorePreprocessor, MotionAnimator {
   This method is called when an interactive animation is in place
   The plugin should pause the animation, and seek to the given progress
   - Parameters:
-     - elapsedTime: time of the animation to seek to.
+     - progress: time of the animation to seek to.
   */
-  open func seek(to elapsedTime: TimeInterval) {}
+  open func seek(to progress: TimeInterval) {}
  /**
   For supporting interactive animation only.
@@ -111,10 +111,10 @@ class MotionPlugin: MotionCorePreprocessor, MotionAnimator {
   This method is called when an interactive animation is ended
   The plugin should resume the animation.
   - Parameters:
-   - elapsedTime: will be the same value since last `seekTo`
+   - progress: will be the same value since last `seekTo`
   - reverse: a boolean value indicating whether or not the animation should reverse
   */
-  open func resume(at elapsedTime: TimeInterval, isReversed: Bool) -> TimeInterval { return 0 }
+  open func resume(at progress: TimeInterval, isReversed: Bool) -> TimeInterval { return 0 }
  /**
   For supporting interactive animation only.

--- a/Sources/MotionProgressRunner.swift
+++ b/Sources/MotionProgressRunner.swift
@@ -29,7 +29,7 @@
 import UIKit
 protocol MotionProgressRunnerDelegate: class {
-    func update(elapsedTime: TimeInterval)
+    func update(progress: TimeInterval)
    func complete(isFinishing: Bool)
 }
@@ -61,7 +61,7 @@ class MotionProgressRunner {
            return
        }
-        delegate?.update(elapsedTime: timePassed / duration)
+        delegate?.update(progress: timePassed / duration)
    }
    func start(timePassed: TimeInterval, totalTime: TimeInterval, reverse: Bool) {

--- a/Sources/MotionTransitionObserver.swift
+++ b/Sources/MotionTransitionObserver.swift
@@ -32,7 +32,7 @@ public protocol MotionTargetStateObserver {
    /**
     Executed when the elapsed time changes during a transition.
     - Parameter transitionObserver: A MotionTargetStateObserver. 
-     - Parameter didUpdateWith elapsedTime: A TimeInterval.
+     - Parameter didUpdateWith progress: A TimeInterval.
     */
-    func motion(transitionObserver: MotionTargetStateObserver, didUpdateWith elapsedTime: TimeInterval)
+    func motion(transitionObserver: MotionTargetStateObserver, didUpdateWith progress: TimeInterval)
 }
--- a/Sources/Transition/MotionTransition+Animate.swift
+++ b/Sources/Transition/MotionTransition+Animate.swift
@@ -75,13 +75,10 @@ extension MotionTransition {
        // We don't want fromView to layout after our animation starts.
        // Therefore we kick off the layout beforehand
        fromView?.layoutIfNeeded()
        for animator in animators {
            let duration = animator.animate(fromViews: animatingFromViews.filter {
-                print(animator.canAnimate(view: $0, isAppearing: false))
                return animator.canAnimate(view: $0, isAppearing: false)
            }, toViews: animatingToViews.filter {
-                print(animator.canAnimate(view: $0, isAppearing: false))
                return animator.canAnimate(view: $0, isAppearing: true)
            })
@@ -99,7 +96,7 @@ extension MotionTransition {
        } else if let startingProgress = startingProgress {
           update(startingProgress)
        } else if animatorWantsInteractive {
-            update(elapsedTime: 0)
+            update(0)
        } else {
            complete(after: totalDuration, isFinishing: true)
        }

--- a/Sources/Transition/MotionTransition+Complete.swift
+++ b/Sources/Transition/MotionTransition+Complete.swift
@@ -45,9 +45,9 @@ extension MotionTransition {
            return
        }
-        let totalTime = after / (isFinishing ? max((1 - elapsedTime), 0.01) : max(elapsedTime, 0.01))
+        let totalTime = after / (isFinishing ? max((1 - progress), 0.01) : max(progress, 0.01))
-        progressRunner.start(timePassed: elapsedTime * totalTime, totalTime: totalTime, reverse: !isFinishing)
+        progressRunner.start(timePassed: progress * totalTime, totalTime: totalTime, reverse: !isFinishing)
    }
    /**
@@ -84,7 +84,7 @@ extension MotionTransition {
            animators.removeAll()
            plugins.removeAll()
            context = nil
-            elapsedTime = 0
+            progress = 0
            totalDuration = 0
            state = .possible
        }

--- a/Sources/Transition/MotionTransition+CustomTransition.swift
+++ b/Sources/Transition/MotionTransition+CustomTransition.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.
+ */
+import UIKit
+extension MotionTransition {
+    /**
+     A helper transition function.
+     - Parameter from: A UIViewController.
+     - Parameter to: A UIViewController.
+     - Parameter in view: A UIView.
+     - Parameter completion: An optional completion handler.
+     */
+    public func transition(from: UIViewController, to: UIViewController, in view: UIView, completion: ((Bool) -> Void)? = nil) {
+        guard !isTransitioning else {
+            return
+        }
+        state = .notified
+        isPresenting = true
+        transitionContainer = view
+        fromViewController = from
+        toViewController = to
+        completionCallback = { [weak self] in
+            guard let `self` = self else {
+                return
+            }
+            completion?($0)
+            self.state = .possible
+        }
+        start()
+    }
+}
--- a/Sources/Transition/MotionTransition+Interactive.swift
+++ b/Sources/Transition/MotionTransition+Interactive.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.
+ */
+import UIKit
+extension MotionTransition {
+    /**
+     Updates the elapsed time for the interactive transition.
+     - Parameter progress t: the current progress, must be between -1...1.
+     */
+    func update(_ percentageComplete: TimeInterval) {
+        guard .animating == state else {
+            startingProgress = percentageComplete
+            return
+        }
+        progressRunner.stop()
+        progress = 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.
+     */
+    func finish(isAnimated: Bool = true) {
+        guard .animating == state || .notified == state || .starting == state else {
+            return
+        }
+        guard isAnimated else {
+            complete(isFinishing: true)
+            return
+        }
+        var d: TimeInterval = 0
+        for a in animators {
+            d = max(d, a.resume(at: progress * totalDuration, isReversed: false))
+        }
+        complete(after: d, isFinishing: true)
+    }
+    /**
+     Cancel the interactive transition.
+     Will stop the interactive transition and animate from the
+     current state to the **begining** state
+     - Parameter isAnimated: A boolean indicating if the completion is animated.
+     */
+    func cancel(isAnimated: Bool = true) {
+        guard .animating == state || .notified == state || .starting == state else {
+            return
+        }
+        guard isAnimated else {
+            complete(isFinishing: false)
+            return
+        }
+        var d: TimeInterval = 0
+        for a in animators {
+            var t = progress
+            if t < 0 {
+                t = -t
+            }
+            d = max(d, a.resume(at: t * totalDuration, isReversed: true))
+        }
+        complete(after: d, isFinishing: false)
+    }
+    /**
+     Override transition animations during an interactive animation.
+     For example:
+     Motion.shared.apply([.position(x:50, y:50)], to: view)
+     will set the view's position to 50, 50
+     - Parameter modifiers: An Array of MotionModifier.
+     - Parameter to view: A UIView.
+     */
+    func apply(modifiers: [MotionModifier], to view: UIView) {
+        guard .animating == state else {
+            return
+        }
+        let targetState = MotionTargetState(modifiers: modifiers)
+        if let otherView = context.pairedView(for: view) {
+            for animator in animators {
+                animator.apply(state: targetState, to: otherView)
+            }
+        }
+        for animator in self.animators {
+            animator.apply(state: targetState, to: view)
+        }
+    }
+}
--- a/Sources/Transition/MotionTransition+Start.swift
+++ b/Sources/Transition/MotionTransition+Start.swift
@@ -40,12 +40,27 @@ extension MotionTransition {
        prepareViewFrame()
        prepareViewControllers()
        prepareSnapshotView()
+        preparePlugins()
        preparePreprocessors()
        prepareAnimators()
-        preparePlugins()
+        for v in plugins {
+            preprocessors.append(v)
+            animators.append(v)
+        }
        prepareTransitionContainer()
        prepareContainer()
        prepareContext()
+        for v in preprocessors {
+            v.motion = self
+        }
+        for v in animators {
+            v.motion = self
+        }
        prepareViewHierarchy()
        prepareAnimatingViews()
        prepareToView()
@@ -83,14 +98,10 @@ fileprivate extension MotionTransition {
    /// Prepares the snapshot view, which hides any flashing that may occur.
    func prepareSnapshotView() {
-        guard let v = transitionContainer else {
+        fullScreenSnapshot = transitionContainer?.window?.snapshotView(afterScreenUpdates: false) ?? fromView?.snapshotView(afterScreenUpdates: false)
-            return
-        }
-        fullScreenSnapshot = v.window?.snapshotView(afterScreenUpdates: false) ?? fromView?.snapshotView(afterScreenUpdates: false)
        if let snapshot = fullScreenSnapshot {
-            (v.window ?? v)?.addSubview(snapshot)
+            (transitionContainer?.window ?? transitionContainer)?.addSubview(snapshot)
        }
        if let v = fromViewController?.motionStoredSnapshot {
@@ -104,60 +115,35 @@ fileprivate extension MotionTransition {
        }
    }
+    /// Prepares the plugins.
+    func preparePlugins() {
+        plugins = MotionTransition.enabledPlugins.map {
+            return $0.init()
+        }
+    }
    /// Prepares the preprocessors.
    func preparePreprocessors() {
-        for x in [IgnoreSubviewTransitionsPreprocessor(),
+        preprocessors = [IgnoreSubviewTransitionsPreprocessor(),
                         ConditionalPreprocessor(),
                         TransitionPreprocessor(),
                         MatchPreprocessor(),
                         SourcePreprocessor(),
-                  CascadePreprocessor()] as [MotionPreprocessor] {
+                         CascadePreprocessor()]
-                preprocessors.append(x)
-        }
-        for v in preprocessors {
-            v.motion = self
-        }
    }
    /// Prepares the animators.
    func prepareAnimators() {
-        animators.append(MotionTargetStateAnimator<MotionCoreAnimationViewContext>())
+        animators = [MotionTargetStateAnimator<MotionCoreAnimationViewContext>()]
        if #available(iOS 10, tvOS 10, *) {
            animators.append(MotionTargetStateAnimator<MotionViewPropertyViewContext>())
        }
-        for v in animators {
-            v.motion = self
-        }
-    }
-    /// Prepares the plugins.
-    func preparePlugins() {
-        for x in MotionTransition.enabledPlugins.map({
-            return $0.init()
-        }) {
-            plugins.append(x)
-        }
-        for plugin in plugins {
-            preprocessors.append(plugin)
-            animators.append(plugin)
-        }
    }
    /// Prepares the transition container.
    func prepareTransitionContainer() {
-        guard let v = transitionContainer else {
+        transitionContainer?.isUserInteractionEnabled = false
-            return
-        }
-        v.isUserInteractionEnabled = false
-        // a view to hold all the animating views
-        container = UIView(frame: v.bounds)
-        v.addSubview(container!)
    }
    /// Prepares the view that holds all the animating views.
@@ -193,24 +179,16 @@ fileprivate extension MotionTransition {
        tv.updateConstraintsIfNeeded()
        tv.setNeedsLayout()
        tv.layoutIfNeeded()
+        context.set(fromViews: fv.flattenedViewHierarchy, toViews: tv.flattenedViewHierarchy)
    }
    /// Prepares the view hierarchy.
    func prepareViewHierarchy() {
-        guard let fv = fromView else {
+        if (.auto == viewOrderStrategy &&
-            return
-        }
-        guard let tv = toView else {
-            return
-        }
-        context.set(fromViews: fv.flattenedViewHierarchy, toViews: tv.flattenedViewHierarchy)
-        if (viewOrderStrategy == .auto &&
            !isPresenting &&
            !isTabBarController) ||
-            viewOrderStrategy == .sourceViewOnTop {
+            .sourceViewOnTop == viewOrderStrategy {
            context.insertToViewFirst = true
        }
    }
@@ -226,6 +204,8 @@ fileprivate extension MotionTransition {
            return false
        }
+        print("FROM PREPARED", animatingFromViews)
        animatingToViews = context.toViews.filter { (view) -> Bool in
            for animator in animators {
                if animator.canAnimate(view: view, isAppearing: true) {
@@ -234,6 +214,8 @@ fileprivate extension MotionTransition {
            }
            return false
        }
+        print("TO PREPARED", animatingFromViews)
    }
    /// Prepares the to view.

--- a/Sources/Transition/MotionTransition.swift
+++ b/Sources/Transition/MotionTransition.swift
@@ -119,7 +119,7 @@ public protocol MotionViewControllerDelegate {
 #### Use the following methods for controlling the interactive transition:
 ```swift
- func update(progress:Double)
+ func update(progress: Double)
 func end()
 func cancel()
 func apply(transitions: [MotionTargetState], to view: UIView)
@@ -348,7 +348,7 @@ open class MotionTransition: NSObject {
    internal var fullScreenSnapshot: UIView?
    /// Progress of the current transition. 0 if no transition is happening.
-    public internal(set) var elapsedTime: TimeInterval = 0 {
+    public internal(set) var progress: TimeInterval = 0 {
        didSet {
            guard .animating == state else {
                return
@@ -362,7 +362,7 @@ open class MotionTransition: NSObject {
                updatePlugins()
            }
-            transitionContext?.updateInteractiveTransition(CGFloat(elapsedTime))
+            transitionContext?.updateInteractiveTransition(CGFloat(progress))
        }
    }
@@ -418,8 +418,8 @@ open class MotionTransition: NSObject {
 }
 extension MotionTransition: MotionProgressRunnerDelegate {
-    func update(elapsedTime: TimeInterval) {
+    func update(progress: TimeInterval) {
-        self.elapsedTime = elapsedTime
+        self.progress = progress
    }
 }
@@ -446,13 +446,13 @@ fileprivate extension MotionTransition {
        }
        for v in observers {
-            v.motion(transitionObserver: v, didUpdateWith: elapsedTime)
+            v.motion(transitionObserver: v, didUpdateWith: progress)
        }
    }
    /// Updates the animators.
    func updateAnimators() {
-        let t = elapsedTime * totalDuration
+        let t = progress * totalDuration
        for a in animators {
            a.seek(to: t)
        }
@@ -460,87 +460,13 @@ fileprivate extension MotionTransition {
    /// Updates the plugins.
    func updatePlugins() {
-        let t = elapsedTime * totalDuration
+        let t = progress * totalDuration
        for p in plugins where p.requirePerFrameCallback {
            p.seek(to: t)
        }
    }
 }
-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(_ percentageComplete: TimeInterval) {
-        guard .animating == state else {
-            startingProgress = percentageComplete
-            return
-        }
-        progressRunner.stop()
-        elapsedTime = Double(CGFloat(percentageComplete).clamp(0, 1))
-    }
-    /**
-     Cancel the interactive transition.
-     Will stop the interactive transition and animate from the
-     current state to the **begining** state
-     - Parameter isAnimated: A boolean indicating if the completion is animated.
-     */
-    public func cancel(isAnimated: Bool = true) {
-        guard isTransitioning else {
-            return
-        }
-        guard isAnimated else {
-            complete(isFinishing: false)
-            return
-        }
-        var d: TimeInterval = 0
-        for a in animators {
-            var t = elapsedTime
-            if t < 0 {
-                t = -t
-            }
-            d = max(d, a.resume(at: t * totalDuration, isReversed: true))
-        }
-        complete(after: d, isFinishing: false)
-    }
-    /**
-     Override transition animations during an interactive animation.
-     For example:
-     Motion.shared.apply([.position(x:50, y:50)], to: view)
-     will set the view's position to 50, 50
-     - Parameter modifiers: An Array of MotionModifier.
-     - Parameter to view: A UIView.
-     */
-    public func apply(modifiers: [MotionModifier], to view: UIView) {
-        guard .animating == state else {
-            return
-        }
-        let targetState = MotionTargetState(modifiers: modifiers)
-        if let otherView = context.pairedView(for: view) {
-            for animator in animators {
-                animator.apply(state: targetState, to: otherView)
-            }
-        }
-        for animator in self.animators {
-            animator.apply(state: targetState, to: view)
-        }
-    }
-}
 internal extension MotionTransition {
    /**
     Checks if a given plugin is enabled.
@@ -597,30 +523,6 @@ public extension MotionTransition {
    }
 }
-public extension MotionTransition {
-    /**
-     A helper transition function.
-     - Parameter from: A UIViewController.
-     - Parameter to: A UIViewController.
-     - Parameter in view: A UIView.
-     - Parameter completion: An optional completion handler.
-     */
-    func transition(from: UIViewController, to: UIViewController, in view: UIView, completion: ((Bool) -> Void)? = nil) {
-        guard !isTransitioning else {
-            return
-        }
-        state = .notified
-        isPresenting = true
-        transitionContainer = view
-        fromViewController = from
-        toViewController = to
-        completionCallback = completion
-        start()
-    }
-}
 internal extension MotionTransition {
    /**
     Processes the start transition delegation methods.