In the past I mentioned a good tutorial on creating an Angry Birds like game with Cocos2d and the Chipmunk physics engine (using the SpaceManager wrapper).
I’ve come across an excellent tutorial that while creating a similar takes a different approach using the Box2D game engine. The tutorial uses a catapult to fire at the structures, and creates a much more polished result with a scrolling camera, Box2D joints, and more.
Here’s a video demonstrating the end result in action:
The tutorial is from Gustavo Ambrozio, and can be found in 2 parts here:
How To Make a Catapult Shooting Game with Cocos2D and Box2D Part 1
How To Make a Catapult Shooting Game with Cocos2D and Box2D Part 2
A very high quality step-by-step tutorial on building an Angry Birds like game with Box2D and Cocos2D that should get you off to a great start if you’re looking to build this type of game.