Add support for copying animation traits. (#30)

src/MDMAnimationTraits.h

@@ -24,7 +24,7 @@
 /**
  A generic representation of animation traits.
  */
-@interface MDMAnimationTraits: NSObject
+@interface MDMAnimationTraits: NSObject <NSCopying>
 
 /**
  Initializes the instance with the provided duration and kCAMediaTimingFunctionEaseInEaseOut timing

src/MDMAnimationTraits.m

@@ -80,6 +80,15 @@ - (instancetype)initWithDelay:(NSTimeInterval)delay
   return self;
 }
 
+#pragma mark - NSCopying
+
+- (id)copyWithZone:(NSZone *)zone {
+  return [[[self class] alloc] initWithDelay:self.delay
+                                    duration:self.duration
+                                 timingCurve:[self.timingCurve copyWithZone:zone]
+                                  repetition:[self.repetition copyWithZone:zone]];
+}
+
 @end
 
 @implementation MDMAnimationTraits (SystemTraits)

src/MDMRepetition.h

@@ -21,7 +21,7 @@
 /**
  Represents repetition that repeats a specific number of times.
  */
-@interface MDMRepetition: NSObject <MDMRepetitionTraits>
+@interface MDMRepetition: NSObject <NSCopying, MDMRepetitionTraits>
 
 /**
  Initializes the instance with the given number of repetitions.

src/MDMRepetition.m

@@ -39,5 +39,12 @@ - (instancetype)initWithNumberOfRepetitions:(double)numberOfRepetitions
   return self;
 }
 
+#pragma mark - NSCopying
+
+- (id)copyWithZone:(__unused NSZone *)zone {
+  return [[[self class] alloc] initWithNumberOfRepetitions:self.numberOfRepetitions
+                                              autoreverses:self.autoreverses];
+}
+
 @end
 

src/MDMRepetitionOverTime.h

@@ -21,7 +21,7 @@
 /**
  Represents repetition that repeats until a specific duration has passed.
  */
-@interface MDMRepetitionOverTime: NSObject <MDMRepetitionTraits>
+@interface MDMRepetitionOverTime: NSObject <NSCopying, MDMRepetitionTraits>
 
 /**
  Initializes the instance with the given duration.

src/MDMRepetitionOverTime.m

@@ -38,5 +38,11 @@ - (instancetype)initWithDuration:(double)duration autoreverses:(BOOL)autoreverse
   return self;
 }
 
+#pragma mark - NSCopying
+
+- (id)copyWithZone:(__unused NSZone *)zone {
+  return [[[self class] alloc] initWithDuration:self.duration autoreverses:self.autoreverses];
+}
+
 @end
 

src/MDMRepetitionTraits.h

@@ -19,7 +19,7 @@
 /**
  A generalized representation of a repetition traits.
  */
-@protocol MDMRepetitionTraits <NSObject>
+@protocol MDMRepetitionTraits <NSObject, NSCopying>
 
 /**
  Whether the animation should animate backwards after animating forwards.

src/MDMSpringTimingCurve.h

@@ -22,7 +22,7 @@
 /**
  A timing curve that represents the motion of a single-dimensional attached spring.
  */
-@interface MDMSpringTimingCurve: NSObject <MDMTimingCurve>
+@interface MDMSpringTimingCurve: NSObject <NSCopying, MDMTimingCurve>
 
 /**
  Initializes the timing curve with the given parameters and an initial velocity of zero.

src/MDMSpringTimingCurve.m

@@ -89,6 +89,20 @@ - (void)setInitialVelocity:(CGFloat)initialVelocity {
   _coefficientsAreInvalid = YES;
 }
 
+#pragma mark - NSCopying
+
+- (id)copyWithZone:(NSZone *)zone {
+  MDMSpringTimingCurve *copy =
+      [[[self class] allocWithZone:zone] initWithMass:self.mass
+                                              tension:self.tension
+                                             friction:self.friction
+                                      initialVelocity:self.initialVelocity];
+  copy->_coefficientsAreInvalid = _coefficientsAreInvalid;
+  copy->_duration = _duration;
+  copy->_dampingRatio = _dampingRatio;
+  return copy;
+}
+
 #pragma mark - Private
 
 - (void)recalculateCoefficientsIfNeeded {

src/MDMTimingCurve.h

@@ -20,5 +20,5 @@
 /**
  A generalized representation of a timing curve.
  */
-@protocol MDMTimingCurve <NSObject>
+@protocol MDMTimingCurve <NSObject, NSCopying>
 @end

tests/unit/MDMAnimationTraitsTests.swift

@@ -126,4 +126,38 @@ class MDMAnimationTraitsTests: XCTestCase {
       XCTAssertEqual(setRepetition.autoreverses, repetition.autoreverses)
     }
   }
+
+  func testModifyingACopyDoesNotModifyTheOriginal() {
+    let spring = MDMSpringTimingCurve(mass: 0.7, tension: 0.8, friction: 0.9)
+    let repetition = MDMRepetition(numberOfRepetitions: 5)
+    let traits = MDMAnimationTraits(delay: 0.2,
+                                    duration: 0.5,
+                                    timingCurve: spring,
+                                    repetition: repetition)
+
+    let copy = traits.copy() as! MDMAnimationTraits
+    copy.delay = copy.delay + 1
+    copy.duration = copy.duration + 1
+    if let springCopy = copy.timingCurve as? MDMSpringTimingCurve {
+      springCopy.friction = springCopy.friction + 1
+      springCopy.tension = springCopy.tension + 1
+      springCopy.mass = springCopy.mass + 1
+      springCopy.initialVelocity = springCopy.initialVelocity + 1
+
+      XCTAssertNotEqualWithAccuracy(springCopy.friction, spring.friction, 0.001)
+      XCTAssertNotEqualWithAccuracy(springCopy.tension, spring.tension, 0.001)
+      XCTAssertNotEqualWithAccuracy(springCopy.mass, spring.mass, 0.001)
+      XCTAssertNotEqualWithAccuracy(springCopy.initialVelocity, spring.initialVelocity, 0.001)
+    }
+    if let repetitionCopy = copy.repetition as? MDMRepetition {
+      repetitionCopy.autoreverses = !repetitionCopy.autoreverses
+      repetitionCopy.numberOfRepetitions = repetitionCopy.numberOfRepetitions + 1
+
+      XCTAssertNotEqual(repetitionCopy.autoreverses, repetition.autoreverses)
+      XCTAssertNotEqual(repetitionCopy.numberOfRepetitions, repetition.numberOfRepetitions)
+    }
+
+    XCTAssertNotEqualWithAccuracy(copy.duration, traits.duration, 0.001)
+    XCTAssertNotEqualWithAccuracy(copy.delay, traits.delay, 0.001)
+  }
 }