There are two ways to include files in your project that guarantees compilation. Only one of these ways should be used at a time.
I like my fonts antialiased, and one thing that has continually bothered me is Xcode's lack of antialiasing in its code editor. To gain this "feature" I had to go to the Xcode Preferences window, then to the Fonts and Colors section. Click on the font and either change it to another fixed width font, or increase the size of Monaco to be greater than 10. For some reason, even if it's set in System Preferences, Monaco at 10 point or lower is not antialiased (except for in the Terminal, which has its own antialiasing setting).