The head first book is good, but the people that I have taught with it, that have had development backgrounds tended to outgrow it's linear approach before they got to the end of the book. That can either be looked at as good or bad, it definitely get's you up and running quick, but it is a poor substitute for a book that can be used as a reference after you learn the platform. I remember reading that one of the books was updated for the new IOS and xCode, which is important because a lot of stuff changed. You can get lost in a tutorial due to the fact that so much has changed. Make sure you either use the old xCode or get a book that covers the new xCode.