UINavigationBar

In this section, you are going to give the UINavigationBar a descriptive title for the UIViewController that is currently on top of the UINavigationController’s stack.

Every UIViewController has a navigationItem property of type UINavigationItem. However, unlike UINavigationBar, UINavigationItem is not a subclass of UIView, so it cannot appear on the screen. Instead, the navigation item supplies the navigation bar with the content it needs to draw. When a UIViewController comes to the top of a UINavigationController’s stack, the UINavigationBar uses the UIViewController’s navigationItem to configure itself, as shown in Figure 13.10.

Figure 13.10  UINavigationItem

By default, a UINavigationItem is empty. ...

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