you have several options, but this are my personal recommendations:
First a very good book about iPhone programming, from the code master Aaron Hillegas:
ios_programming_the_big_nerd_ranch_guide
then you can advance in more advanced stuff like learn the awesome Cocos 2D framework with this book:
Learn-iPhone-iPad-cocos2d-Development
This asumming that you have already a good base in C and Objective-C programming languages, if not i will recommend you this book:
The C Programming Language
The Objective-C Programming Language
With this books you will have a good amount of fun, cheers.