Some time ago I faced with problem - to write crossplatform application with GUI, but it should not contain any tool-specific resources like MSVC rc files, or xcode resources. It should build GUI in the most native way. Simplify problem: there was the following interface in existing code base, that I have to satisfy.
The most strange code here is setActivationPolicy code line. It allows window to be activated, receive keyboard and mouse event and more. I spent a lot of time to find it (this was my first macosx experience).
As for addition, we could add custom NSView to our window, here the defenition of derived view.
That’s all. Yes, this is not the most minimal cocoa application, but it is created without usage of xcode magic, and includes not-big code :) The most interesting and hard things have been found at cocoa with love.