Chaining Core Animation animations

You can also use animation grouping and use the beginTime field of the animation. Try something like this:

CABasicAnimation *posAnimation = [CABasicAnimation animationWithKeyPath:@"position"];[posAnimation setFromValue:[NSNumber numberWithFloat:0.0]];[posAnimation setToValue:[NSNumber numberWithFloat:1.0]];// Here's the important part[posAnimation setDuration:10.0];[posAnimation setBeginTime:0.0];CABasicAnimation *borderWidthAnimation = [CABasicAnimation animationWithKeyPath:@"borderWidth"];[borderWidthAnimation setFromValue:[NSNumber numberWithFloat:0.0]];[borderWidthAnimation setToValue:[NSNumber numberWithFloat:1.0]];// Here's the important part[borderWidthAnimation setDuration:10.0];[borderWidthAnimation setBeginTime:5.0];CAAnimationGroup *group = [CAAnimationGroup animation];[group setDuration:10.0];[group setAnimations:[NSArray arrayWithObjects:posAnimation, borderWidthAnimation, nil]];[layer addAnimation:group forKey:nil];

Notice that the duration of the entire animation is 10 seconds. The first one starts at second 0 and the second one starts at 5 seconds.

As Matt pointed out, you can create animation groups that consist of different animations for the same layer with different begin times. You can also set a delegate for stand-alone CAAnimation objects or CAAnimation Groups and as each animation finishes it will call an animationDidStop:finished: delegate method (note that animations that are part of a group won't call their delegate's animationDidStop:finished: method.

I figured out a cool trick that makes using the CAAnimation animationDidStop:finished: method more powerful. I use the method setValue:forKey: to add a block of code to a stand-alone animation or animation group, with the key @"animationCompletionBlock". I then write a general animationDidStop:finished: method that checks the just-completed animation for a @"animationCompletionBlock" key, and if it finds it, execute the block of code there.

Take a look at this project on github for a working example of that technique:

CAAnimation demo with completion blocks

You an also Set a group of animations inside a

[CATransaction begin];//...[[CATransaction commit];

block, as you suggested. When you do that, you can using the CATransaction class method setCompletionBlock: to invoke a block of code when all the animations in the current transaction group complete. The completion block for one transaction can then trigger the next transaction.

I pull this off using the setCompletionBlock method to define a closure that triggers the next animation when the first one is finished:

[CATransaction begin]layer1.property = new_property;CATransaction.setCompletionBlock {    [CATransaction begin]    layer2.property2 = new_property2;    [CATransaction commit];}[CATransaction commit];