How do I pause all animations in a layer tree?

A: In order to pause animations in a layer tree, you can take advantage of the fact that a CALayer conforms to the CAMediaTiming protocol. The CAMediaTiming protocol defines, among other things, a speed with which its timeline progresses, which you can use to pause all animations on the target layer. Listing 1 demonstrates how you can do this.

Listing 1  Pause and Resume animations.

-(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; }