Is there a way to pause a CABasicAnimation?
I have a basic spinning animation of the iPhone. Is there any way that I can "pause" the animation so that the position of the view will be maintained? I guess one way of doing this would be to cause the animation to "complete" instead of calling "remove" on it, how would I do that?
CABasicAnimation* rotationAnimation;
rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
rotationAnimation.toValue = [NSNumber numberWithFloat: M_PI * 2];
rotationAnimation.duration = 100;
rotationAnimation.cumulative = YES;
rotationAnimation.repeatCount = HUGE_VALF;
rotationAnimation.removedOnCompletion = NO;
rotationAnimation.fillMode = kCAFillModeForwards;
[myView.layer addAnimation:rotationAnimation forKey:@"rotationAnimation"];
Recently appeared Apple's technical note QA1673 describes how to pause/resume layer's animation.
Pause and resume animations listing is below:
-(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;
}
Edit: iOS 10 introduced new API - UIViewPropertyAnimator that allows to handle animations more interactively, for example it makes easy to pause and resume animation or 'seek' it to some particular progress value.
Answer For Swift 3:
Credits @Vladimir
Code:
func pauseAnimation(){
var pausedTime = layer.convertTime(CACurrentMediaTime(), fromLayer: nil)
layer.speed = 0.0
layer.timeOffset = pausedTime
}
func resumeAnimation(){
var pausedTime = layer.timeOffset
layer.speed = 1.0
layer.timeOffset = 0.0
layer.beginTime = 0.0
let timeSincePause = layer.convertTime(CACurrentMediaTime(), fromLayer: nil) - pausedTime
layer.beginTime = timeSincePause
}
设置视图图层的当前状态以匹配presentationLayer的状态，然后删除动画：
CALayer *pLayer = [myView.layer presentationLayer];
myView.layer.transform = pLayer.transform;
[myView.layer removeAnimationForKey:@"rotationAnimation"];