Question

UIView animatWithDuration has an optional param for completion, but I need one for update

The whole idea is I need a block that runs on EVERY frame of animation. I figure I can spoof this with a NSInterval, but that just seems hoaky.

Thoughts?

Answer 1

Use CADisplayLink instead. Works just like an NSTimer, but fires exactly once every frame and will be perfectly in sync with the animation.

Here’s how you set one up:

self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(step)];
[link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];

Your animation code

- (void)step
{
    //do something related to your animation
}

Then when the animation finishes

[self.displayLink invalidate];
self.displayLink = nil;