有没有办法暂停CABasicAnimation？
我有一个iPhone的基本旋转动画。 有什么办法可以“暂停”动画，以保持视图的位置？ 我想这样做的一种方式是导致动画“完成”而不是调用“删除”它，我将如何做到这一点？
CABasicAnimation* rotationAnimation;
rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
rotationAnimation.toValue = [NSNumber numberWithFloat: M_PI * 2];
rotationAnimation.duration = 100;
rotationAnimation.cumulative = YES;
rotationAnimation.repeatCount = HUGE_VALF;
rotationAnimation.removedOnCompletion = NO;
rotationAnimation.fillMode = kCAFillModeForwards;
[myView.layer addAnimation:rotationAnimation forKey:@"rotationAnimation"];
最近出现的Apple的技术说明QA1673描述了如何暂停/恢复图层的动画。
下面暂停和恢复动画列表：
-(void)pauseLayer:(CALayer*)layer
{
CFTimeInterval pausedTime = [layer convertTime:CACurrentMediaTime() fromLayer:nil];
layer.speed = 0.0;
layer.timeOffset = pausedTime;
}
-(void)resumeLayer:(CALayer*)layer
{
CFTimeInterval pausedTime = [layer timeOffset];
layer.speed = 1.0;
layer.timeOffset = 0.0;
layer.beginTime = 0.0;
CFTimeInterval timeSincePause = [layer convertTime:CACurrentMediaTime() fromLayer:nil] - pausedTime;
layer.beginTime = timeSincePause;
}
编辑： iOS 10引入了新的API - UIViewPropertyAnimator，它允许更交互地处理动画，例如它可以很容易地暂停和恢复动画，或者将它“查找”到某个特定的进度值。
Swift 3的答案：
Credits @Vladimir
码：
func pauseAnimation(){
var pausedTime = layer.convertTime(CACurrentMediaTime(), fromLayer: nil)
layer.speed = 0.0
layer.timeOffset = pausedTime
}
func resumeAnimation(){
var pausedTime = layer.timeOffset
layer.speed = 1.0
layer.timeOffset = 0.0
layer.beginTime = 0.0
let timeSincePause = layer.convertTime(CACurrentMediaTime(), fromLayer: nil) - pausedTime
layer.beginTime = timeSincePause
}
设置视图图层的当前状态以匹配presentationLayer的状态，然后删除动画：
CALayer *pLayer = [myView.layer presentationLayer];
myView.layer.transform = pLayer.transform;
[myView.layer removeAnimationForKey:@"rotationAnimation"];