What is a UIViewController

问题:

I know what a UIView is but not a UIViewController. I just want to know what I could use it for, and what it is compared to a UIView

回答1:

Basically you need to know, what is model-view-controller architecture in the software engineering field, the UIView corresponds to view of this architecture and UIViewController is at controller side of this architecture.

Now UIViewController can be thought as an agent that controls (and has the implementations of methods) the events and design of the UIView that is shown on the screen. Anything you want to change on the view can be written inside a method in its controller class, that inherits itself from UIViewController class. That is only the brief description of this big concept. For details you should look for the above link.