Graphics Libraries

Drawing stuff directly in ios gets a bit slow as soon as you have more than a few images onscreen. So we should use a library like:

Cocos 2d tutorial
Cocos 2d with Box2d tutorial

For the more hard core there is Open GL

For full cross platform 3D goodness at a minimum $400 price tag (plus you'd need a copy of Maya) there is the rather awesome looking: Unity