How to identify CAAnimation within the animationDidStop delegate?

I had a problem where I had a series of overlapping CATransition / CAAnimation sequences, all of which I needed to perform custom operations when the animations stopped, but I only wanted one delegate handler for animationDidStop.

However, I had a problem, there didn't appear to be a way to uniquely identify each CATransition / CAAnimation in the animationDidStop delegate.

I solved this problem via the key / value system exposed as part of CAAnimation.

When you start your animation use the setValue method on the CATransition / CAAnimation to set your identifiers and values to use when animationDidStop fires:

-(void)volumeControlFadeToOrange
{   
    CATransition* volumeControlAnimation = [CATransition animation];
    [volumeControlAnimation setType:kCATransitionFade];
    [volumeControlAnimation setSubtype:kCATransitionFromTop];
    [volumeControlAnimation setDelegate:self];
    [volumeControlLevel setBackgroundImage:[UIImage imageNamed:@"SpecialVolume1.png"] forState:UIControlStateNormal];
    volumeControlLevel.enabled = true;
    [volumeControlAnimation setDuration:0.7];
    [volumeControlAnimation setValue:@"Special1" forKey:@"MyAnimationType"];
    [[volumeControlLevel layer] addAnimation:volumeControlAnimation forKey:nil];    
}

- (void)throbUp
{
    doThrobUp = true;

    CATransition *animation = [CATransition animation]; 
    [animation setType:kCATransitionFade];
    [animation setSubtype:kCATransitionFromTop];
    [animation setDelegate:self];
    [hearingAidHalo setBackgroundImage:[UIImage imageNamed:@"m13_grayglow.png"] forState:UIControlStateNormal];
    [animation setDuration:2.0];
    [animation setValue:@"Throb" forKey:@"MyAnimationType"];
    [[hearingAidHalo layer] addAnimation:animation forKey:nil];
}

In your animationDidStop delegate:

- (void)animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)flag{

    NSString* value = [theAnimation valueForKey:@"MyAnimation