Do you want to know the nuts and bolts of developing iPhone games using xCode? icodeblog has the right reference source for you. The tutorial comes complete with images, codes that you’ll need to develop a simple Tennis game. 

The tutorial has three parts, the first part deals with the creation of different folders within the main project folder.  The second part talks about user interaction, Simple game AI, game logic etc.The third and the final part contains integration of the game.

If you are interested to learn about iPhone game programming, this tutorial would give you the basic idea. View the tutorial here.