Comment by mwd_

It's probably a lot easier to understand a larger project like a game or a website by trying to implement something substantial on your own. A lot of the obvious approaches to coding that work for small examples don't scale well for one reason or another. In the process of running into roadblocks and finding solutions (typically with the help of google) you'll encounter some of the pieces that end up in something like an iPhone app and at that point you'll probably be in a much better position to understand them.