smoothly stopping a core animation rotation

Question

How do you stop the rotation of a custom drawn CALayer on the iPhone?

This

CATransform3D pausetransform = ((CALayer *)[layer presentationLayer]).transform;
[layer removeAllAnimations];
layer.transform = pausetransform;

stops the animation, then immediately rotates the layer back a little bit. Probably because after the pausetransform value is set the animation continues for a short while.

Setting the layer.transform value in the animation's - (void) animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)finishednormally delegate method briefly displays the layer in the starting position of the animation before it rotates to the correct position.

Answer 1

Another way is to call

[view.layer removeAnimationForKey:@"name of your animation"];

However, in both removes, depending on how you set up the animation, the animation stops at the next iteration of the animation. If, let's say, you were spinning in 10 degree increments, the animation would stop before the next 10 degree increment.

Answer 2

It turns out the UIActionSheet I was setting up when calling [layer removeAllAnimations] took so long to display it was postponing the actual stopping of the animation. By moving the setup of the UIActionSheet to the - (void) animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)finishednormally delegate method the rotation now stops smoothly.