Model View Controller

'Model-View-Controller' (MVC) is an implementation architecture often used for user-interfaces. It allows for a separation between the implementation of the visible aspects of a user-interface and the logic that governs its behaviour. Unfortunately, the term MVC is used to mean quite different things by different people. This document attempts to explain some of the architectures that are described as being "MVC" and point out their differences.

MVC in Apple's Cocoa Framework

Apple's Cocoa framework gives strong support for the use of MVC - in fact it is almost a requirement for proper use of the Cocoa framework. As explained in Apple's doc about Cocoa design patterns, the model objects encapsulate data and behaviour, the view objects present information to the user and allow for interaction, and the controller objects intermediate between the model objects and the view objects. The controller objects "know" about the model objects and the view objects, but the model and view don't "know" about each other - all data flow goes via the controller. At Apple's developer conference "WWDC 2003", James Dempsey sang a song about MVC.