IOS 中动画的暂停与继续播放的详解

- (void)pauselayer:(CALayer *)layer 
{ 
  CFTimeInterval pausedTime = [layer convertTime:CACurrentMediaTime() fromLayer:nil]; 
  layer.speed = 0.0; 
  layer.timeOffset = pausedTime; 
} 

- (void)playlayer:(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; 
} 

// 暂停 
[self pauselayer:self.label01.layer]; 
// 继续 
[self playlayer:self.label01.layer];