I already programmed in Objective-C, I studied cocoa (I read big nerd ranch's cocoa programming for mac os x) and some iOS programming but not with iOS 7. I know the language and basic stuff like multithreading, using blocks, ARC,etc... but I still know too few about iOS. For some reason I don't like iTunesU lessons, I prefer a book (it's also faster for me to read a book because I can better organize and skip parts that I don't need). Now I've seen many books online, but I still don't know which one to choose. Considering that my goal is to learn how to distribute apps on the app store (I need to know how to sandbox an app, right?), which book would you suggest to me?