This is the tutorial I used to get to darrinm's answer. It's updated for ios5/6 and really easy. When I'm popular enough I'll delete this and add it as a comment to his answer.
http://www.raywenderlich.com/5492/working-with-json-in-ios-5
http://www.touch-code-magazine.com/tutorial-fetch-and-parse-json-in-ios6/