Technical Q&A QA1673
How to pause the animation of a layer tree
Q: 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; } |
Document Revision History
Date | Notes |
---|---|
2011-08-22 | Fixed typo in code listing. |
2010-06-02 | New document that describes how you can pause animations in a layer tree |
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