While there are several books on programming for Mac OS X, Advanced Mac OS X Programming: The Big Nerd Ranch Guide is the only one that contains explanations of how to leverage the powerful underlying technologies. This book gets down to the real nitty-gritty. The third edition is updated for Mac OS X 10.5 and 10.6 and covers new technologies like DTrace, Instruments, Grand Central Dispatch, blocks, and NSOperation.
Advanced Mac OSX Programming Dalrymple, Advanced Mac OS X Instructor at The Big Nerd Ranch, illuminates Mac OS X's plumbing through nitty-gritty insights that separate great OS X programmers from beginners. His book covers multithreading, IPC, networking, Bonjour, and UNIX APIs, and much more. Full description