If your application is a document-based drawing application, DrawKit can play a major role in providing the core “engine” that you need. In fact, this is its main design focus. In such an application, a document (NSDocument subclass) will typically own a DKDrawing instance and arrange for one or more DKDrawingViews to display and interact with it. To make this approach even easier, you could base your document class on DKDrawingDocument.
DKDrawingDocument is an NSDocument subclass that owns a DKDrawing and arranges for it to be created when the document is initialised or opened from a file on disk. It also provides an outlet called m_mainView which you can hook up to a DKDrawingView in Interface Builder (of course if you have other arrangements in mind you can easily extend this approach). DKDrawingDocument automatically connects a valid DKDrawingView on that outlet to the DKDrawing instance it creates via a suitable controller, so it very much “just works” for this typical case.
The important thing to remember is the M-V-C design - you need all three: model, view and controller for the Drawkit system to hang together and function. DKDrawingDocument makes these connections if you use it, but if you prefer to go it alone, you need to make these connections yourself. Recall that DKDrawing owns its controllers (DKViewController or subclass), the view is owned by its superview or window, and the drawing itself must be owned by some other object - typically the document.