The source code for Wolfenstein on the iPhone is all C they have just used the AppDelegate as an entry point to the app and to call their C functions to run the game. (Obviously they use Obj-C for iPhone specific stuff such as accelerometer etc but the core of the game is all C)
In fact the code is a very interesting read to anyone who is mainly a C developer as it demonstrates the use of heavy C code on the iPhone and would answer most of your questions