iOS Programming: The Big Nerd Ranch Guide, 6th Edition

5 View Controllers

A view controller is an instance of a subclass of UIViewController. A view controller manages a view hierarchy. It is responsible for creating view objects that make up the hierarchy and for handling events associated with the view objects in its hierarchy.

So far, WorldTrotter has a single view controller, ConversionViewController. In this chapter, you will update it to use multiple view controllers. The user will be able to switch between two view hierarchies – one for viewing the ConversionViewController and another for displaying a map (Figure 5.1).

Figure 5.1  The two faces of WorldTrotter

The views ...