Stop an auto-reverse / infinite-repeat UIView animation with a BOOL / completion block

问题

I'm setting up the following UIView animateWithDuration: method, with the intention of setting my animationOn BOOL elsewhere in the program to cancel that infinite looped repeat. I was under the impression that the completion block would be called each time a cycle of the animation ends, but this doesn't appear to be the case.

Is the completion block ever called in a repeating animation? And if not, is there another way I can stop this animation from outside this method?

- (void) animateFirst: (UIButton *) button
{
    button.transform = CGAffineTransformMakeScale(1.1, 1.1);
    [UIView animateWithDuration: 0.4
                          delay: 0.0
                        options: UIViewAnimationOptionCurveEaseOut | UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat
                     animations: ^{
                         button.transform = CGAffineTransformIdentity;
                     } completion: ^(BOOL finished){
                         if (!animationOn) {
                             [UIView setAnimationRepeatCount: 0];
                         }
    }];
}

回答1:

The completion block will only get called when the animation is interrupted. For example it gets called when the app goes in the background and comes back to the foreground again (via multitasking). In that case the animation is stopped. You should restart the animation when that happens.

To stop the animation you can remove it from the view's layer:

[button.layer removeAllAnimations];

回答2:

Old but another option.

You can also setup another animation which is not repeating on the same view, that way you can also capture it in the current state and return it to how it is by using the option UIViewAnimationOptionBeginFromCurrentState. Your completion block is also called.

-(void)someEventSoStop
{
    button.transform = CGAffineTransformMakeScale(1.0, 1.0);
    [UIView animateWithDuration: 0.4
                          delay: 0.0
                        options: UIViewAnimationOptionCurveEaseOut | UIViewAnimationOptionBeginFromCurrentState
                     animations: ^{
                         button.transform = CGAffineTransformIdentity;
                     } completion: ^(BOOL finished){

                     }];
}

回答3:

I've solved the problem by calling [button.layer removeAllAnimations].

回答4:

As per the documentation of View class reference: If you used any of the class methods such as animateWithDuration:delay:options:animations:completion: if the duration is set to negative value or 0, the changes are made without performing animation. so I did something like this to stop the infinite animation:

[UIView animateWithDuration:0.0 animations:^{
      button.layer.affineTransform = CGAffineTransformIdentity;
  }];

I think this is better than removing all animations from the layer as in the suggested answer. Note that this is applicable for all other class animation methods in the UIView class.

来源：https://stackoverflow.com/questions/13991465/stop-an-auto-reverse-infinite-repeat-uiview-animation-with-a-bool-completion