I'm in the process of trying to learn Objective-C. In the beginning this can be really rough. There are so many brackets. So many brackets...
This site has been pretty helpful in trying to make some sense out of the chaos:
This is the video course I'm learning from: Coding Together: Developing Apps for iPhone and iPad (Winter 2013). It's really good, better than most books I've read and it's free.
Programming iOS 6 however has been a fantastic book and explains obj-c in great depth. You'll need at least a basic understanding of either C or C++. Other books have you blindly follow code examples without explaining anything. This book tells you exactly what's going on. I wish more books were written in this fashion.
There's lot of other stuff obj-c does that seem auto-magical. Like the variables that are created from that are prefixed with an _. It's all about comments you guys.