(http://www.zenbrains.com/blog/wp-content/uploads/2010/07/fully-illustrated-cocos2d.jpg)
cocos2d for iPhone is a framework for building 2D games, demos, and other graphical/interactive applications. It is based on the cocos2d design: it uses the same concepts, but instead of using python it uses objective-c.
cocos2d for iPhone is:
Easy to use: it uses a familiar API, and comes with lots of examples
Fast: it uses the OpenGL ES best practices and optimized data structures
Flexible: it is easy to extend, easy to integrate with 3rd party libraries
Free: is open source, compatible both with closed and open source games
Community supported: cocos2d has an active, big and friendly community (forum, IRC)
AppStore approved: More than 2500 AppStore games already use it, including many best seller games.
cocos2d for iPhone supports: iPod Touch, iPhone, iPad and OS X
Features:
Scene management (workflow)
Transitions between scenes
Sprites and Sprite Sheets
Effects: Lens, Ripple, Waves, Liquid, Twirl, etc.
Actions (behaviors):
Trasformation Actions: Move, Rotate, Scale, Jump, etc.
Composable actions: Sequence, Spawn, Repeat, Reverse
Ease Actions: Exp, Sin, Cubic, etc.
Misc actions: CallFunc, OrbitCamera
Basic menus and buttons
Integrated physics engine (both Box2d and Chipmunk)
Particle system
Text rendering support (variable and fixed width fonts)
Texture Atlas support
Tile Map support (TMXmaps):
Orthogonal maps
Isometric maps
Hexagonal maps
Parallax scrolling support
Sound support
Streak Motion support
Render Texture support
High Score server (Cocos Live)
Point based API: Supports Retina Display
Touch/Accelerometer support (iOS). Keyboard / Mouse support (Mac)
Portrait and Landscape mode (iOS) / Automatic Fullscreen support (Mac)
Integrated Pause/Resume
Fast Textures:Supports PVRTC textures, 8-bit textures, 16-bit textures and 32-bit textures
Language: objective-c
OpenGL ES 1.1 based (iOS) / OpenGL 1.5 based (Mac)
En otras palabras es un Framework que nos sirve para programar aplicacion para iOS de forma nativa, usando codigo Objective-C
solo se puede usar si tenemos una Mac aunke en teoria si tenemos una makina virtual con mac podrémos usarlo sin problema
Pagina Oficial (http://www.cocos2d-iphone.org/)