ios animation的暂停pause、恢复resume

项目中要用到动画的控制，比如说暂停、恢复继续等，先看代码：（很容易实现）

-(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;
}

如果在一个view中我们添加了多个动画，（不是组合动画），同样容易实现动画的暂停、恢复，方法就是为每个动画层layer调用上面的方法，比如我的方法如下，我用的是三个单独动画的组合效果，就是如下调用的

-(void)stopAnimation;
{
NSLog(@"停止动画");
//[_customView.layer removeAllAnimations];
[self pauseLayer:_customView1.layer];
[self pauseLayer:_customView2.layer];
[self pauseLayer:_customView3.layer];
}

-(void)resumeAnimation
{
[self resumeLayer:_customView1.layer];
[self resumeLayer:_customView2.layer];
[self resumeLayer:_customView3.layer];

}