Came here to say pretty much the same thing. I've never seen a good Objective-C programmer give any other response to this question than the Hillegass book. You

Came here to say pretty much the same thing. I've never seen a good Objective-C programmer give any other response to this question than the Hillegass book. You should have a knowledge of C, or at least programming in general, but the whole book is a lot of excellently-written tutorials, expanding on each app bit by bit. An excellent resource.