I received a nice reading list recommendation via email in response to this first post on Mac Development. Here is the recommendation:
Kochan’s, "Objective C" is a great book. On the other hand, Garfinkle and Mahoney is very much out of date to the point that many in the community are upset that O’Reilly still sells the book without a caveat. The Cocoa they were writing about is circa 2000 or 2001. A great deal, mainly from Tiger and even Jaguar, has changed since then.
A better book would be Aaron Hillegass’, "Cocoa Programming for Mac OS X", 2nd ed. Aaron’s book is based on his Cocoa Bootcamp, an intense week of A-Z in Cocoa programming. Although a bit long in the tooth, though not as much as G & M, Anguish and Yacktman’s, "Cocoa Programming" is a great tome for filling in
the details that Aaron may gloss over. And no book recommendation would be worth much without mentioning, "Cocoa Recipies for OS X’ by Cheeseman.
Also recommended by a friend: Advanced Mac OSX Programming – by Mark Dalrymple