Question

The name “View Controller” in iOS programming is a bit confusing as it includes both words “View” and “Controller” in the MVC model. Is “View Controller” actually just another name for Controller (as the view is actually mostly done by the Interface Builder). Why is it called a “View Controller”? Is it because this controller does all the view properties updating and event handling as well?

Answer 1

Yes, a UIViewController lives inside the “Controller” layer of MVC. But it is a special controller that controls and updates a view. View controllers can also handle events because they derive from UIResponder.

You can also create general controllers by subclassing NSObject. For example an accounts controller that manages accounts etc. You actually find other controller classes in the iOS SDK, e.g. UIDocumentInteractionController.

From the iOS View Controller Programming Guide:

For iOS applications, view controllers provide a vital link between an
application’s data and its visual appearance. Understanding when and
how to use view controllers is crucial to the design of iOS
applications. View controllers are traditional controller objects in
the Model-View-Controller design paradigm but they also do much more.
In iOS applications, view controllers provide much of the logic needed
to manage basic application behaviors. For example, view controllers
manage the presentation and removal of content from the screen and
they manage the reorientation of views in response to device
orientation changes.