This is an admirable effort, but I would not recommend ever using this in practice. I am saying this from experience: I wrote a game engine on top of UIKit, which I spent months trying to fine-tune before finally ditching it and re-writing everything to use Cocos2d.

The performance aspect is just not there. Once you get to a game with a large number of sprites and animations, animations will jitter and glitch. You're really going to be stretching what Core Animation can handle.

What I usually recommend these days is to use Cocos2d for your main game view, but using UIKit for the rest of the interface (menus, score screens, etc.).