Update 1/9/2013: Fully updated for Cocos2D 2.1-beta4 (original post by Ray Wenderlich, update by Brian Broom). Box2D is a powerful physics library that comes with the Cocos2D game programming library for the iPhone. There’s a lot you can do with it, and a great way to start learning about how it works is to create a simple game with it! In this tutorial, we are going to create a simple Breakout ga