在CAKeyframeAnimation之后，UIButton不会接收到触摸

Question

My situation: I've a UIButton that it's animate with a CAKeyframeAnimation that's declared as a category on UIView :

    CAKeyframeAnimation * scale =  [CAKeyframeAnimation animationWithKeyPath:@"transform.scale"];
    scale.duration = duration;
    scale.beginTime = delay;
    scale.fillMode = kCAFillModeForwards;

    NSMutableArray * times = [[NSMutableArray alloc] init];

    scale.values = values;
    scale.timingFunctions = times;

    CAAnimationGroup * group = [CAAnimationGroup animation];
    [group setDelegate:self];
    [group setDuration:duration + delay];
    [group setFillMode:kCAFillModeForwards];
    [group setRemovedOnCompletion:NO];
    [group setAnimations:[NSArray arrayWithObject:scale]];

    [self.layer addAnimation:group forKey:@"scale"];

The problem is that after the animation, the button doesn't receive touch. If I remove the animation all works fine. Does anyone know what I'm doing wrong ?

Thanks

Answer 1

You shouldn't use kCAFillModeForwards and removedOnCompletion = NO to stick the animated layer in the final position. This will not work for a control, and results in the behavior you noticed.

Instead, set the final state for the button before adding the animation to it's layer.

self.layer.transform = CGAffineTransformMakeScale(finalScaleX, finalScaleY);
[self.layer addAnimation:group forKey:@"scale"];

Answer 2

The problem is that the animation only changes the presentation of the button but the touch target is still the same as before. You should either remove the animation after completion and set the transform on the button or ht test the presentation layer.

I wrote about hit testing animating layers in a blog post that explains it in more detail.

Answer 3

You must insert the following line of code self.layer.transform = CGAffineTransformMakeScale(finalScaleX, finalScaleY); when the animation is ended.