Debugging Physics Body and Shapes
If you ever wish to have red boxes drawn around your physics bodies to aid
in debugging, simple add these 2 lines to your core, where it makes sense to you.
AppDelegate is a good place.
Using the built-in physics engine is a good idea. It is solid and advanced. However, if you wish to use an alternative physics engine you can. All you need to do is disabling CC_USE_PHYSICS in base/ccConfig.h.