Add support for animating anchorPoint. (#97)

Author: jverkoey

src/MDMAnimatableKeyPaths.h

@@ -42,6 +42,16 @@
 NS_SWIFT_NAME(AnimatableKeyPath)
 typedef NSString * const MDMAnimatableKeyPath CF_TYPED_ENUM;
 
+/**
+ Anchor point.
+
+ Equivalent UIView property: N/A
+ Equivalent CALayer property: anchorPoint
+ Expected value type: CGPoint or NSValue (containing a CGPoint).
+ Additive animation supported: No.
+ */
+FOUNDATION_EXPORT MDMAnimatableKeyPath MDMKeyPathAnchorPoint NS_SWIFT_NAME(anchorPoint);
+
 /**
  Background color.
 

src/MDMAnimatableKeyPaths.m

@@ -16,6 +16,7 @@
 
 #import "MDMAnimatableKeyPaths.h"
 
+MDMAnimatableKeyPath MDMKeyPathAnchorPoint = @"anchorPoint";
 MDMAnimatableKeyPath MDMKeyPathBackgroundColor = @"backgroundColor";
 MDMAnimatableKeyPath MDMKeyPathBounds = @"bounds";
 MDMAnimatableKeyPath MDMKeyPathBorderWidth = @"borderWidth";

src/private/CABasicAnimation+MotionAnimator.m

@@ -17,6 +17,7 @@
 #import "CABasicAnimation+MotionAnimator.h"
 
 #import "CAMediaTimingFunction+MotionAnimator.h"
+#import "MDMAnimatableKeyPaths.h"
 
 #import <UIKit/UIKit.h>
 
@@ -66,7 +67,9 @@ static BOOL IsAnimationKeyPathAlwaysNonAdditive(NSString *keyPath) {
   static NSSet *nonAdditiveKeyPaths = nil;
   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
-    nonAdditiveKeyPaths = [NSSet setWithArray:@[@"backgroundColor", @"opacity"]];
+    nonAdditiveKeyPaths = [NSSet setWithArray:@[MDMKeyPathAnchorPoint,
+                                                MDMKeyPathBackgroundColor,
+                                                MDMKeyPathOpacity]];
   });
 
   return [nonAdditiveKeyPaths containsObject:keyPath];

src/private/MDMBlockAnimations.m

@@ -27,7 +27,8 @@
   static NSSet *animatableKeyPaths = nil;
   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
-    animatableKeyPaths = [NSSet setWithArray:@[MDMKeyPathBackgroundColor,
+    animatableKeyPaths = [NSSet setWithArray:@[MDMKeyPathAnchorPoint,
+                                               MDMKeyPathBackgroundColor,
                                                MDMKeyPathBorderWidth,
                                                MDMKeyPathBorderColor,
                                                MDMKeyPathBounds,

tests/unit/MotionAnimatorBehavioralTests.swift

@@ -43,6 +43,7 @@ class AnimatorBehavioralTests: XCTestCase {
   }
 
   private let properties: [AnimatableKeyPath: Any] = [
+    .anchorPoint: CGPoint(x: 0.2, y: 0.4),
     .backgroundColor: UIColor.blue,
     .borderWidth: 5,
     .borderColor: UIColor.red,

tests/unit/QuartzCoreBehavioralTests.swift

@@ -69,6 +69,7 @@ class QuartzCoreBehavioralTests: XCTestCase {
 
   func testWhichPropertiesImplicitlyAnimateButNotAdditively() {
     let properties: [AnimatableKeyPath: Any] = [
+      .anchorPoint: CGPoint(x: 0.2, y: 0.4),
       .borderWidth: 5,
       .borderColor: UIColor.red,
       .bounds: CGRect(x: 0, y: 0, width: 123, height: 456),

tests/unit/UIKitBehavioralTests.swift

@@ -113,6 +113,7 @@ class UIKitBehavioralTests: XCTestCase {
 
   func testSomePropertiesImplicitlyAnimateButNotAdditively() {
     let baselineProperties: [AnimatableKeyPath: Any] = [
+      .anchorPoint: CGPoint(x: 0.2, y: 0.4),
       .backgroundColor: UIColor.blue,
       .opacity: 0.5,
     ]

tests/unit/UIKitEquivalencyTests.swift

@@ -100,6 +100,7 @@ class UIKitEquivalencyTests: XCTestCase {
 
   func testSomePropertiesImplicitlyAnimateButNotAdditively() {
     let baselineProperties: [AnimatableKeyPath: Any] = [
+      .anchorPoint: CGPoint(x: 0.2, y: 0.4),
       .backgroundColor: UIColor.blue,
       .borderColor: UIColor.red,
       .opacity: 0.5,