reworked MatchPreprocessor

Sources/Animator/MotionAnimator.swift

@@ -44,7 +44,7 @@ public protocol MotionAnimator: class {
     func canAnimate(view: UIView, isAppearing: Bool) -> Bool
     
     /**
-     Animates the from-views to the to-views.
+     Animates the fromViews to the toViews.
      - Parameter fromViews: An Array of UIViews.
      - Parameter toViews: An Array of UIViews.
      - Returns: A TimeInterval.

Sources/Animator/MotionDefaultAnimator.swift

@@ -81,7 +81,7 @@ extension MotionDefaultAnimator {
     }
     
     /**
-     Animates the from-views to the to-views.
+     Animates the fromViews to the toViews.
      - Parameter fromViews: An Array of UIViews.
      - Parameter toViews: An Array of UIViews.
      - Returns: A TimeInterval.

Sources/Animator/MotionHasInsertOrder.swift

@@ -27,6 +27,6 @@
  */
 
 internal protocol MotionHasInsertOrder: class {
-    /// A boolean indicating whether to insert the to-view first or not.
+    /// A boolean indicating whether to insert the toView first or not.
     var insertToViewFirst: Bool { get set }
 }

Sources/Motion.swift

@@ -174,7 +174,7 @@ public class Motion: MotionController {
      */
     internal var forceNonInteractive = false
 
-    /// Inserts the to-views first.
+    /// Inserts the toViews first.
     internal var insertToViewFirst = false
     
     /// Indicates whether a UINavigationController is transitioning.
@@ -198,12 +198,12 @@ public class Motion: MotionController {
         return !isContainerController && (.overFullScreen == toViewController!.modalPresentationStyle || .overCurrentContext == toViewController!.modalPresentationStyle)
     }
 
-    /// A reference to the from-view, fromViewController.view.
+    /// A reference to the fromView, fromViewController.view.
     internal var fromView: UIView {
         return fromViewController!.view
     }
     
-    /// A reference to the to-view, toViewController.view.
+    /// A reference to the toView, toViewController.view.
     internal var toView: UIView {
         return toViewController!.view
     }

Sources/MotionContext.swift

@@ -70,7 +70,7 @@ public class MotionContext {
 
 internal extension MotionContext {
     /**
-     Sets the from-views and to-views within the transition context.
+     Sets the fromViews and toViews within the transition context.
      - Parameter fromViews: An Array of UIViews.
      - Parameter toViews: An Array of UIViews.
      */

Sources/MotionController.swift

@@ -115,7 +115,7 @@ public class MotionController: NSObject {
     /// An Array of MotionPlugins used during a transition.
     internal var plugins: [MotionPlugin]!
 
-    /// The matching from-views to to-views based on the motionIdentifier value.
+    /// The matching fromViews to toViews based on the motionIdentifier value.
     internal var transitionPairs: [(fromViews: [UIView], toViews: [UIView])]!
 
     /// Plugins that are enabled during the transition.
@@ -320,7 +320,7 @@ internal extension MotionController {
         preparePlugins()
     }
     
-    /// Prepares the transition from-view & to-view pairs.
+    /// Prepares the transition fromView & toView pairs.
     func prepareTransitionPairs() {
         guard isTransitioning else {
             fatalError()

Sources/Preprocessors/MatchPreprocessor.swift

@@ -33,45 +33,50 @@ class MatchPreprocessor: MotionPreprocessor {
     weak var context: MotionContext!
     
     /**
-     Implementation for processor.
+     Processes the transitionary views.
      - Parameter fromViews: An Array of UIViews.
      - Parameter toViews: An Array of UIViews.
      */
     func process(fromViews: [UIView], toViews: [UIView]) {
         for tv in toViews {
-            guard let id = tv.motionIdentifier, let fv = context.sourceView(for: id) else { continue }
+            guard let i = tv.motionIdentifier, let fv = context.sourceView(for: i) else { continue }
             
             var tvState = context[tv] ?? MotionTransitionState()
             var fvState = context[fv] ?? MotionTransitionState()
             
-            if let beginStateIfMatched = tvState.beginStateIfMatched {
-                tvState.append(.beginWith(transitions: beginStateIfMatched))
+            if let v = tvState.beginStateIfMatched {
+                tvState.append(.beginWith(transitions: v))
             }
-            if let beginStateIfMatched = fvState.beginStateIfMatched {
-                fvState.append(.beginWith(transitions: beginStateIfMatched))
+            
+            if let v = fvState.beginStateIfMatched {
+                fvState.append(.beginWith(transitions: v))
             }
             
-            // match is just a two-way source effect
-            tvState.motionIdentifier = id
-            fvState.motionIdentifier = id
+            tvState.motionIdentifier = i
+            tvState.opacity = 0
             
+            fvState.motionIdentifier = i
             fvState.arc = tvState.arc
             fvState.duration = tvState.duration
             fvState.timingFunction = tvState.timingFunction
             fvState.delay = tvState.delay
             fvState.spring = tvState.spring
             
-            tvState.opacity = 0
             let forceNonFade = tvState.nonFade || fvState.nonFade
             let isNonOpaque = !fv.isOpaque || fv.alpha < 1 || !tv.isOpaque || tv.alpha < 1
+            
             if !forceNonFade && isNonOpaque {
-                // cross fade if from/toViews are not opaque
+                // Cross fade if from/toViews are not opaque.
                 fvState.opacity = 0
+                
             } else {
-                // no cross fade in this case, fromView is always displayed during the transition.
+                // No cross fade in this case, fromView is always displayed during the transition.
                 fvState.opacity = nil
                 
-                // we dont want two shadows showing up. Therefore we disable toView's shadow when fromView is able to display its shadow
+                /**
+                 We dont want two shadows showing up. Therefore we disable toView's
+                 shadow when fromView is able to display its shadow.
+                 */
                 if !fv.layer.masksToBounds && fvState.displayShadow {
                     tvState.displayShadow = false
                 }