Books on OBJ-C (OSX)

only graphical app experience i have is from 8 years ago when i first tried using tk with perl and some tcl.

i've just recently started learning xcode and interface builder after i bought a macbook and i'm kinda hooked on this shit now so i wanna buy an objective c book.

tl;dr: recommend some good books on obj-c that deal with osx if possible.

got sick of waiting on u gais so i ordered o'reillys obj-c with cocoa. seems perfect because i've been using c for so long so obj-c should be easy, i mainly need to learn how cocoa binds to the language and how you use these bindings.