Useful Links

 Apple

  iOS Dev Center

iOS Developer Library                                             

Xcode Glossary

iOS Simulator Users Guilde

Sanford

 Developing iOS 7 Apps for iPhone and iPad

Wikipedia

Cocoa Touch

Objective -C

Free BSD

format strings

LLVM Technology

Overview

Compiler

TabBar Image Creation

Tutorial

Free online editor

Other Stuff

31 Days of iOS

stackoverflow.com  (a great place to ask questions)