I have an application that's not based on storyboards, but rather xib files. Main.xib contains the main application window. However, it's just a window. There's no NSWindowController. How can one be added?
Ok, figured it out. You simply add a new object to the scene, change its class to whichever NSWindowController subclass you want it to work with, attach the window to its output, then set an output to hold the window controller itself. I recommend on the app delegate.
I took things a step further by also changing the window to not show on launch, and I removed the window from the App Delegate (since it now has a reference to the window controller and thus the window indirectly already). This way I can center the window before actually showing it.
Only caveat to look out for is that you won't get the window-loading overrides since the window is handed to the VC, not loaded by it, so any code you need to run only when the window is set, simply override the window variable and add a didSet section. Works like a charm!
Still, I may try to dig deeper to see if I can update the Window controller to load the window normally so I can get those events as designed.