When you create a new iOS app project in Xcode, you get to choose between several project templates, from the aptly named “Empty Application” to specialized things like an “OpenGL Game”. I noticed that beginners can feel overwhelmed by so much choice. Which starting point should I choose? What if I go with a “Single View Application” now but later decide that I really wanted a tab bar in my app? Do I have to start over?
Ole goes on to explain each of the various templates and the accompanying options (units tests, core data, etc).
This is a good overview if you are new to Xcode.