Implemented drawRect: method in VertexView class. Launching the app now shows a VertexView taking up the whole window. Snazzy!
Created GraphViewController class and a corresponding xib file.
Making sure that autoresizing mask of GraphViewController's view is not translated into constraints. That would conflict with autolayout constraints to be set up at a later stage.
Added public graph property in GraphViewController class.
Set up an IBOutlet graphView connected to an NSView filling the entire AppDelegate window.
The test code now makes the view of the GraphViewController take up the entire window using autolayout constraints.
Created a new GraphView class.
Set GraphViewController's view to be a GraphView.