CoreAnimation之CALayer基础
CoreAnimation之变换
CoreAnimation之常用图层
修改非RootLayer的一些属性(支持隐式动画的属性)会产生隐式动画
隐式动画的持续时间取决于当前事务，隐式动画的类型取决于图层行为
事务：
事务实际上是Core Animation用来包含一系列属性动画集合的机制，任何用指定事务去改变可以做动画的图层属性都不会立刻发生变化，而是当事务一旦提交的时候开始用一个动画过渡到新值
所谓事务，具体到代码中就是CATransaction类，CATransaction没有属性或者实例方法，并且也不能用+alloc和-init方法创建它，常用方法有这些：
/* Begin a new transaction for the current thread; nests. */
+ (void)begin;
/* Commit all changes made during the current transaction. Raises an
* exception if no current transaction exists. */
+ (void)commit;
/* Commits any extant implicit transaction. Will delay the actual commit
* until any nested explicit transactions have completed. */
+ (void)flush;
/* Methods to lock and unlock the global lock. Layer methods automatically
* obtain this while modifying shared state, but callers may need to lock
* around multiple operations to ensure consistency. The lock is a
* recursive spin-lock (i.e shouldn't be held for extended periods). */
+ (void)lock;
+ (void)unlock;
/* Accessors for the "animationDuration" per-thread transaction
* property. Defines the default duration of animations added to
* layers. Defaults to 1/4s. */
+ (CFTimeInterval)animationDuration;
+ (void)setAnimationDuration:(CFTimeInterval)dur;
/* Accessors for the "animationTimingFunction" per-thread transaction
* property. The default value is nil, when set to a non-nil value any
* animations added to layers will have this value set as their
* "timingFunction" property. Added in Mac OS X 10.6. */
+ (nullable CAMediaTimingFunction *)animationTimingFunction;
+ (void)setAnimationTimingFunction:(nullable CAMediaTimingFunction *)function;
/* Accessors for the "disableActions" per-thread transaction property.
* Defines whether or not the layer's -actionForKey: method is used to
* find an action (aka. implicit animation) for each layer property
* change. Defaults to NO, i.e. implicit animations enabled. */
+ (BOOL)disableActions;
+ (void)setDisableActions:(BOOL)flag;
/* Accessors for the "completionBlock" per-thread transaction property.
* Once set to a non-nil value the block is guaranteed to be called (on
* the main thread) as soon as all animations subsequently added by
* this transaction group have completed (or been removed). If no
* animations are added before the current transaction group is
* committed (or the completion block is set to a different value), the
* block will be invoked immediately. Added in Mac OS X 10.6. */
#if __BLOCKS__
+ (nullable void (^)(void))completionBlock;
+ (void)setCompletionBlock:(nullable void (^)(void))block;
#endif
/* Associate arbitrary keyed-data with the current transaction (i.e.
* with the current thread).
*
* Nested transactions have nested data scope, i.e. reading a key
* searches for the innermost scope that has set it, setting a key
* always sets it in the innermost scope.
*
* Currently supported transaction properties include:
* "animationDuration", "animationTimingFunction", "completionBlock",
* "disableActions". See method declarations above for descriptions of
* each property.
*
* Attempting to set a property to a type other than its document type
* has an undefined result. */
+ (nullable id)valueForKey:(NSString *)key;
+ (void)setValue:(nullable id)anObject forKey:(NSString *)key;
事务有显式事务和隐式事务之分
Core Animation在每个run loop周期中自动开始一次新的事务，即使你不显式的用[CATransaction begin]开始一次事务，任何在一次run loop循环中图层属性的改变都会被集中起来，然后做一次0.25秒的动画，即隐式事务
调用[CATransaction begin]开始一次事务，即为显式事务
举个栗子，新开一个事务，修改layer的backgroundColor:
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
[super touchesBegan:touches withEvent:event];
[CATransaction begin];
//修改动画的持续时间
[CATransaction setAnimationDuration:5.0f];
[CATransaction setCompletionBlock:^{
NSLog(@"动画完成");
}];
layer.backgroundColor = [UIColor blueColor].CGColor;
[CATransaction commit];
}
running.gif
UIView中也有类似的动画机制：
+ (void)beginAnimations:(nullable NSString *)animationID context:(nullable void *)context; // additional context info passed to will start/did stop selectors. begin/commit can be nested
+ (void)commitAnimations; // starts up any animations when the top level animation is commited
iOS 4中引入了block：
+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations NS_AVAILABLE_IOS(4_0); // delay = 0.0, options = 0, completion = NULL
其实两者都在做同样的事，block形式的写法更为简洁
CATransaction的+begin和+commit方法在+animateWithDuration:animations:内部自动调用，这样block中所有属性的改变都会被事务所包含，也可以避免开发者由于对+begin和+commit匹配的失误造成的风险
行为：
为毛我修改layer的backgroundColor，隐式动画的效果一直是渐变呢，为毛不能是淡入淡出或其他效果呢？这就要看图层的行为了
图层行为，实质上是如下几步：
- 图层首先检测它是否有委托，并且是否实现CALayerDelegate协议指定的-actionForLayer:forKey:方法，如果有，直接调用并返回结果
- 如果没有委托，或者委托没有实现-actionForLayer:forKey:方法，图层接着检查包含属性名称对应行为映射的actions字典
- 如果actions字典没有包含对应的属性，那么图层接着在它的style字典接着搜索属性名
- 最后，如果在style里面也找不到对应的行为，那么图层将会直接调用定义了每个属性的标准行为的-defaultActionForKey:方法
我们一步一步试一下：
- 图层首先检测它是否有委托，并且是否实现CALayerDelegate协议指定的-actionForLayer:forKey:方法，如果有，直接调用并返回结果
-(void)viewDidLoad{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.backgroundColor = [UIColor groupTableViewBackgroundColor];
layer = [CALayer layer];
layer.backgroundColor = [UIColor redColor].CGColor;
layer.bounds = CGRectMake(0.0f, 0.0f, 100.0f, 100.0f);
layer.position = self.view.layer.position;
layer.delegate = self;
[self.view.layer addSublayer:layer];
}
-(id)actionForLayer:(CALayer *)layer forKey:(NSString *)event{
NSLog(@"event is : %@",event);
CATransition *transition = [CATransition animation];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromLeft;
return transition;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
[super touchesBegan:touches withEvent:event];
[CATransaction begin];
[CATransaction setAnimationDuration:5.0f];
[CATransaction setCompletionBlock:^{
NSLog(@"completion");
}];
layer.backgroundColor = [UIColor blueColor].CGColor;
[CATransaction commit];
}
-actionForLayer:forKey:需要返回一个遵守
CATransition遵守
CATransition是另一个CAAnimation的子类，和别的子类不同，CATransition有一个type和subtype来标识变换效果，type属性是一个NSString类型，可以被设置成如下类型：
/* Common transition types. */
CA_EXTERN NSString * const kCATransitionFade
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionMoveIn
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionPush
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionReveal
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
subtype用来控制动画方向，提供了如下四种类型：
/* Common transition subtypes. */
CA_EXTERN NSString * const kCATransitionFromRight
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionFromLeft
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionFromTop
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionFromBottom
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
running.gif
- 如果没有委托，或者委托没有实现-actionForLayer:forKey:方法，图层接着检查包含属性名称对应行为映射的actions字典
-(void)viewDidLoad{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.backgroundColor = [UIColor groupTableViewBackgroundColor];
layer = [CALayer layer];
layer.backgroundColor = [UIColor redColor].CGColor;
layer.bounds = CGRectMake(0.0f, 0.0f, 100.0f, 100.0f);
layer.position = self.view.layer.position;
layer.delegate = self;
CATransition *transition = [CATransition animation];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromRight;
layer.actions = @{@"backgroundColor":transition};
[self.view.layer addSublayer:layer];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
[super touchesBegan:touches withEvent:event];
[CATransaction begin];
[CATransaction setAnimationDuration:5.0f];
[CATransaction setCompletionBlock:^{
NSLog(@"completion");
}];
layer.backgroundColor = [UIColor blueColor].CGColor;
[CATransaction commit];
}
running.gif
- 如果actions字典没有包含对应的属性，那么图层接着在它的style字典接着搜索属性名
layer.style = @{@"backgroundColor":transition};
当我给layer的style赋值的时候，却并没有效果，不知道为什么了，愿知道的大神留言教我
呈现图层
当你改变一个图层的属性，属性值的确是立刻更新的（如果你读取它的数据，你会发现它的值在你设置它的那一刻就已经生效了），但是屏幕上并没有马上发生改变。这是因为你设置的属性并没有直接调整图层的外观，相反，他只是定义了图层动画结束之后将要变化的外观
如果你想读取正在动画中的图层的当前属性值，得用这个
/* Returns a copy of the layer containing all properties as they were
* at the start of the current transaction, with any active animations
* applied. This gives a close approximation to the version of the layer
* that is currently displayed. Returns nil if the layer has not yet
* been committed.
*
* The effect of attempting to modify the returned layer in any way is
* undefined.
*
* The `sublayers', `mask' and `superlayer' properties of the returned
* layer return the presentation versions of these properties. This
* carries through to read-only layer methods. E.g., calling -hitTest:
* on the result of the -presentationLayer will query the presentation
* values of the layer tree. */
- (nullable instancetype)presentationLayer;
举个栗子：
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor groupTableViewBackgroundColor];
layer = [CALayer layer];
layer.backgroundColor = [UIColor redColor].CGColor;
layer.bounds = CGRectMake(0.0f, 0.0f, 100.0f, 100.0f);
layer.position = self.view.layer.position;
layer.delegate = self;
[self.view.layer addSublayer:layer];
}
-(void)timerAction{
NSLog(@"presentationLayer.position = %@\tlayer.position = %@",NSStringFromCGPoint(layer.presentationLayer.position),NSStringFromCGPoint(layer.position));
}
//-(id)actionForLayer:(CALayer *)layer forKey:(NSString *)event{
// NSLog(@"event is : %@",event);
// CATransition *transition = [CATransition animation];
// transition.type = kCATransitionPush;
// transition.subtype = kCATransitionFromLeft;
// return transition;
//}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
[super touchesBegan:touches withEvent:event];
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:.5f target:self selector:@selector(timerAction) userInfo:nil repeats:YES];
[CATransaction begin];
[CATransaction setAnimationDuration:5.0f];
[CATransaction setCompletionBlock:^{
NSLog(@"completion");
[timer invalidate];
}];
layer.position = CGPointMake(0.0f, 0.0f);
[CATransaction commit];
}
输出：
屏幕快照 2017-03-09 下午4.09.50.png
但是当我改变layer的默认行为的时候(就是注释的那部分)，presentationLayer就不能获取到正确的值了