You can link frameworks, such as OpenGL.framework and GLUT.framework, by clicking Build Phases at the top of the project editor.
I understand that using GLUT is a kind of old-fashioned way at least on OS X, and maybe I should use Metal instead.
https://developer.apple.com/osx/
OS X El Capitan brings Metal to Mac, giving your apps unprecedented graphics and computing power. With Swift 2.0, you can write even better code thanks to advanced new features. And new extensibility APIs let your apps work seamlessly with Photos and Safari.
Anyway, with GLUT you will get:
