The code you read there was C++, not C. C is very similar to C++, the main difference in that C does not have classes. I don't know any Objective C so I can't comment, but C++ is fairly difficult. The syntax is similar to PHP so that won't give you trouble, but things are overall harder. I initially learned form the book C++ Programming Fundementals by Chuck Easttom and learned from various other resources from both books and the internet after that.

Going specifically to iPhone apps, I have no idea. Mac programming is easier to do than Windows programming, but I have only ever programmed for Windows. You will have to learn your language and a graphics library, probably OpenGL.

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