Taking another trip into the source code editor, we look at how self-documentation helps you move around your code base and find things more quickly. It starts with the symbol menu, the right-most element of the jump bar, which automatically offers quick access to every property, function, method, extension, etc. in the current source file. You can organize this further with special comments to name sections, add dividers, and include to-dos and fix-mes. Next, doc comments on symbols provide a good way to declare your code's interface, and in Xcode you can even write your comments in Markdown to include simple styling and links. Finally, check out the immensely useful open-quickly command, which navigates to the source of any symbol, including those in Apple's frameworks, where you'll sometimes find a very different story from what's in the platform documentation.
Xcode on the Mac App Store: geo.itunes.apple.com/us/app/xcode/id497799835?mt=12&at=10l4Gc
Xcode Treasures eBook: pragprog.com/book/caxcode/xcode-treasures