Question

Is it possible to cancel a UIView animation while it is in progress? Or would I have to drop to the CA level?

i.e. I’ve done something like this (maybe setting an end animation action too):

[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:duration];
[UIView setAnimationCurve: UIViewAnimationCurveLinear];
// other animation properties

// set view properties

[UIView commitAnimations];

But before the animation completes and I get the animation ended event, I want to cancel it (cut it short). Is this possible? Googling around finds a few people asking the same question with no answers – and one or two people speculating that it can’t be done.

Answer 1

The way I do it is to create a new animation to your end point. Set a very short duration and make sure you use the +setAnimationBeginsFromCurrentState: method to start from the current state. When you set it to YES, the current animation is cut short. Looks something like this:

[UIView beginAnimations:nil context:NULL];
[UIView setAnimationBeginsFromCurrentState:YES];
[UIView setAnimationDuration:0.1];
[UIView setAnimationCurve: UIViewAnimationCurveLinear];
// other animation properties

// set view properties

[UIView commitAnimations];