So, I know its probably odd, but I tend to favor video resources when picking up a new language. My process tends to be to go through a great overview series that hits the high concepts, and then use books + internet as a reference for improvement.

For IOS and Obj-C there is one absolute winner for me:

Simon Allardice's Obj-C and iOS courses http://www.lynda.com/Simon-Allardice/21-1.html

He is by far the most thorough and entertaining bald, british, programming teacher ever. Granted, he focuses on the core essentials, but that's generally what you need anyway.

Hope this helps!