iOS CALayer 的 pause 和 resume
// 使用CABasicAnimation时,如果需要暂停动画、恢复动画时可以通过pauseLayer
- (void)pauseLayer:(CALayer*)layer {
if (layer.speed == 0.0) {
return;
}
CFTimeInterval pausedTime = [layer convertTime:CACurrentMediaTime() fromLayer:nil];
layer.speed = 0.0;
layer.timeOffset = pausedTime;
}
- (void)resumeLayer:(CALayer*)layer{
if (layer.speed > 0) {
return;
}
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;
}