cocos2d-iphone is a framework for building 2D games, demos, and other graphical or interactive applications

It is based on the cocos2d design: it uses the same API, but instead of using Python it uses Objective-C.

Main features

Scene management (workflow)
Transitions between scenes
Sprites
Actions
Basic menus and buttons
Integrated Chipmunk 2D physics engine
Particle system
Text rendering support
Texture Atlas support
Tile Map support
Touch/Accelerometer support
Portrait and Landscape mode
Integrated Pause/Resume

Language: Objective-C
Open Source LGPL
OpenGL ES 1.1 based