Recommended Books for learning Objective-C and Cocoa

Since some time I keep busy with learning Objective-C to program on my Mac. There are several good resources in the web. But I like to read books. So I find a very good book to learn the concepts ob Objective-C. It’s Programming in Objective-C from Stephen G. Kocham. If you go further with programming on a Mac you will reach something called Cocoa (pronounced [ko:ko:]). It’s some thing like a rich framework (in deed there are several) which makes it easy to you to program nice (desktop) applications. This is the hardest part because Cocoa covers a very large and powerful API. I found two books dealing with this subject: Cocoa Programming for Mac OS X from Aaron Hillegass and Cocoa Design Patterns from Erik M. Buck and Donald A. Yacktman.