PowenKo, iOS Tutorial 99-1, Game Center ,Game Kit Game Center and cocos2d
Game Kit Game Center and cocos2d reference: http://shawnsbits.com/blog/2010/09/09/game-kit-game-center-and-cocos2d/
iOS, Android, Unity3D Education blog,
Game Kit Game Center and cocos2d reference: http://shawnsbits.com/blog/2010/09/09/game-kit-game-center-and-cocos2d/