Reddit reviews iPhone Application Development For Dummies

Get really familiar with the MVC pattern if you haven't already. It's fundamental in iOS programming. Aside from that, I learned it mostly from a For Dummies book I got at a bookstore. It made a simple app, and I followed along and then made my own using what I learned there. I look at Stack Overflow and the Apple Docs a lot too.

If you want an overview from a business sense, this book might be helpful: http://www.amazon.com/The-Business-iPhone-iPad-Development/dp/1430233001/ref=sr_1_4?ie=UTF8&qid=1346362562&sr=8-4&keywords=iphone+app+development

If you want to actually learn I would recommend one of these:

http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=iphone+app+development

http://www.amazon.com/iPhone-Application-Development-For-Dummies/dp/1118091345/ref=sr_1_3?ie=UTF8&qid=1346362562&sr=8-3&keywords=iphone+app+development

http://www.amazon.com/Beginning-iOS-Development-Exploring-SDK/dp/1430236051/ref=sr_1_7?ie=UTF8&qid=1346362562&sr=8-7&keywords=iphone+app+development