If you review the documentation, you will note that CAAnimationGroup inherits from CAAnimation, and that CAAnimation can only be assigned to one CALayer. It's intent is really to make it easy to create and manage multiple animations you wish to apply to a CALayer at the same time, not to manager animations for multiple CALayer objects.

To handle the sequencing of different animations between different objects, a technique I use is to create an NSOperation for each object/animation, then through them in a NSOperationQueue to manage the sequencing. This is a bit complicated as you have to use the animation completion callback to tell the NSOperation it is finished, but if you write a good animation management subclass of NSOperation, it can be rather convenient and allow you to create sophisticated sequencing paths. The low-rent way of accomplishing the sequencing goal is to simply set the beginTime property on your CAAnimation object (which comes from it's adoption of the CAMediaTiming protocol) as appropriate to get the timing you want.

With that said, I am going to point you to some code that I wrote and open-sourced to solve the exact same use case you describe. You may find it on github here (same code included). I will add the following notes:

• My animation management code allow your to define your animation in a plist by identifying the sequence and timing of image changes, scale changes, position changes, etc. It's actually pretty convenient and cleaner to adjust your animation in a plist file rather than in code (which is why I wrote this).
• If the user is not expected to interact with the subviews you creating, it's actually much better (less overhead) to create layer objects that are added as sub-layers to your hosting view's layer.

If you review the documentation, you will note that CAAnimationGroup inherits from CAAnimation, and that CAAnimation can only be assigned to one CALayer. It's intent is really to make it easy to create and manage multiple animations you wish to apply to a CALayer at the same time, not to manager animations for multiple CALayer objects.

To handle the sequencing of different animations between different CALayer or UIViewobjects, a technique I use is to create an NSOperation for each object/animation, then throw them into a NSOperationQueue to manage the sequencing. This is a bit complicated as you have to use the animation completion callback to tell the NSOperation it is finished, but if you write a good animation management subclass of NSOperation, it can be rather convenient and allow you to create sophisticated sequencing paths. The low-rent way of accomplishing the sequencing goal is to simply set the beginTime property on your CAAnimation object (which comes from it's adoption of the CAMediaTiming protocol) as appropriate to get the timing you want.

With that said, I am going to point you to some code that I wrote and open-sourced to solve the exact same use case you describe. You may find it on github here (same code included). I will add the following notes:

• My animation management code allow your to define your animation in a plist by identifying the sequence and timing of image changes, scale changes, position changes, etc. It's actually pretty convenient and cleaner to adjust your animation in a plist file rather than in code (which is why I wrote this).
• If the user is not expected to interact with the subviews you creating, it's actually much better (less overhead) to create layer objects that are added as sub-layers to your hosting view's layer.