If you’re an experienced iPhone developer, you already know and love the collection of sample projects that come with Xcode–a veritable treasure trove of information. If you’re new, one of the first things you should do is learn how to find them and then actually run each one; it’s the kind of time investment that will pay off in the future (e.g., “How do I do X? Oh wait, I think I remember seeing something like that in one of the sample code apps…“).
Open up your Xcode “Documentation” window and click on the “iPhone OS 2.x Library” doc set on the left-hand side of the window. Then scroll down to the “Resource Types” section and click on the “Sample Code” link.