What prior programming experience do you have?
If the answer is "none", then you're getting a bit ahead of yourself. Learn the basics of C first. Many other's here endorse a variety of books. I, being a student already $30K in debt, instead endorse the free ebook, Learn C The Hard Way.
Check it out here:
http://c.learncodethehardway.org/book/
You don't need to learn everything in the book to move onto learning how to program for the iPhone / Mac, but I suggest going through the first... 17 chapters (up through "Exercise 16: Structs and Pointers to Them". If you get lost during chapters 16 or 17, that's okay... You'll need to understand them eventually, but you can learn through experience while learning how to program the iPhone.
Learning that much C will take you 20-100 hours of reading, writing, studying, and exercising. (The 20 hours is only realistic if you already have other programming experience. It'll take closer to 80 minimum if you have none. So expect it to take between 2 weeks and 2 months, depending on how much time/day you can dedicate to it.)
After you learn that much C, move into the developing for iOS courses offered by Stanford via iTunes U for free. Expect that to take 1-3 months.
Oh, if you're planning on doing 3D games, I'll also tell you a little more: Don't bother with OpenGL. Learning that is a world of pain. I suggest instead learning Ogre 3D:
www.ogre3d.org
But before you learn that, you'll need to learn C++ (IDK any good sources for C++; I learned it in school...) and before you learn C++, you'll need a more solid grasp of C, which means you'll need to make it through the first ~35 chapters of Learn C The Hard way.
Oh, and I'll just throw this out too while I'm at it: if you want to make your own 3D game, with your own models and stuff, you'll likely want to learn Blender and GIMP, too.
So... Yeah. Being able to make your own app or game involves learning a lot. Students go into summer break thinking they'll come out the other end having made a game... But more realistically, they'll probably only learn enough for how to make their game.
