I've heard this is a really good introduction book, http://www.amazon.com/Objective-C-Programming-Ranch-Guide-Gu...

Having read their Cocoa programming for OS X book (http://www.amazon.com/Cocoa-Programming-Mac-3rd-Edition/dp/0...), I can wholeheartedly recommend their books.

'Become an XCoder' free eBook that is a fairly basic introduction to Objective-C and Cocoa programming.

'From C++ to Objective-C' is also good eBook. http://pierre.chachatelier.fr/programmation/fichiers/cpp-obj...

I also bought 'Cocoa Programming for Mac OS X' http://www.amazon.com/Cocoa-Programming-Mac-3rd-Edition/dp/0...

Cocoa is quite different than anything I had programmed before. Once I wrapped my head around nibs, IBOutlets and IBActions it was fairly easy. Once I got going, the apple developer docs were all I needed, but learning I found easier to do from a book than the docs.

I started out developing for the Mac with "The Objective-C Programming Language" but found it clumsy and kind of dense. In my opinion "Cocoa Programming for Mac OS X" by Aaron Hillegass (http://www.amazon.com/Cocoa-Programming-Mac-OS-3rd/dp/032150...) is much better in the way it introduces concepts, and flows from chapter to chapter. Well worth the investment if you're serious about developing for the Mac.

_Cocoa Programming for Mac OS X_[1] by Aaron Hillegass is really great. It's not an iPhone book, but there's enough similarity that it'd still be a really valuable read.

[1] http://www.amazon.com/Cocoa-Programming-Mac-COCOA-PROGRAMMIN...

This one is a must have for the beginner.

http://www.amazon.com/Cocoa-Programming-Mac-OS-3rd/dp/032150...