View nested lists easily!
NSOutlineView is a subclass of
NSTableView that provides a way to display hierarchical data. For example, file hierarchies (though, you’d actually use an
NSBrowser object for a file hierarchy).
NSTreeController is a controller that works with
NSBrowser to manage the data that they display.
In cocoa, controllers are super powerful because they allow you to bypass implementing a lot of the really boring delegate/datasource stuff that you’re forced to do in iOS.
This is a much better explanation of how to set up bindings correctly than I’m currently able to do.