In cocoa, how do you connect the model to viewcontrollers?

Question

So from what I understand the basic application structure for cocoa programs is an AppController in MainMenu.xib. The AppController then initializes the WindowControllers and ViewControllers which has all the UI logic and in turn load the xib files for the rest of the application. The AppController also creates the Model classes.

My confusion is over how to get the data from the model classes into the views. I would like to use bindings and key-value observing. Should each view controller have a pointer to the AppController and the ModelController? If so how would you do that?

[[ViewController alloc] initWithModel:ModelController];

Is the only solution I can think of and it doesnt seem very clean.

Answer 1

I make a controller that creates/loads and owns the model. My application delegate creates and owns this controller.

That same controller usually also owns the window or view; I rarely use dedicated window controllers, and have never used view controllers. If you do use window/view controllers, the model controller would create and own those, too.

Thus, one controller is responsible for both the model (or some specific portion of it) and the (controller for the) window that displays that (portion of the) model.

Answer 2

A common way to link a NSViewController to a model is to set its representedObject value. There is no need to set a pointer to the AppController, as it can always be obtained through [NSApplication sharedApplication].delegate.