You should write a book, called Programming Objective C. That's the book that's missing from O'Reilly's OS X library: One that isn't focused on teaching you how to use Project Builder and such, but concentrates on teaching the basics of C, then the Objective C superset.
Examples should be made using XCode (of Panther), complete with screen shots, so that newbies could see how to compile and run from this standard environment etc. Basically the examples should be of small command line utilities, because if you try to explain Interface Builder at the same time, the book would be all too big. You could simply point to other O'Reilly books on that particular subjects, as reccommended "what do I read now" books.
You could use an appendix to give a quick introduction on how to build a user interface in Interface Builder, and how to connect everything together and add some code. Another appendix should explain _how_ to use, navigate and read Apple's Cocoa API documentation.