From Apple’s View Controller Programming Guide for iOS:
“The most important role of a view controller is to manage a hierarchy of views. Every view controller has a single root view that encloses all of the view controller’s content. To that root view, you add the views you need to display your content.”
Also:
“There are two types of view controllers:
- Content view controllers manage a discrete piece of your app’s content and are the main type of view controller that you create.
- Container view controllers collect information from other view controllers (known as child view controllers) and present it in a way that facilitates navigation or presents the content of those view controllers differently.
Most apps are a mixture of both types of view controllers.”