Cocoa Touch for iPhone OS 3 (Developer Reference)
Jiva DeVoe
I have many iphone programming books and never paid this book much attention. recently though, i have been trying to get a deeper understand of the inner workings of cocoa touch. this book is amazing, its really made me understand the MVC approach used when building iphone apps. the book is well written....and breaks things down to you in a very systematic approach. definitely recommend this book.