Question

I am currently studying UITabBarController in Apple doc but I haven’t clear what is the tab bar interface. Could you explain me this concept? Thank you in advence.

Answer 1

From Apple doc:

This tab bar interface displays tabs at the bottom of the window for
selecting between the different modes and for displaying the views for
that mode.

The view for a tab bar controller is just a container for a tab bar
view and the view containing your custom content.

The tab bar interface is composed by two different parts at glance: a view and the tab bar. The latter is a sort of navigation bar (that is collocated at the bottom of the window) where it’s possible to find different tabs. The tab bar interface has a radio-style selection interface: it means that only one tab can be selected each time. In Apple documentation the tab bar is the bar where you can find tabs named "World Clock", "Alarm", etc. The former instead is the view attached with the UITabBarController (UITabBarController is a UIViewController).

The behaviour of the UITabBarController is quite straight. This controller can contains UIViewController elements. When you create a new UITabBarController and add to it a UIViewController, the view of that UIViewController is attached the view of the UITabBarController.

You can change the current visible content (the bar remains visible) selecting a specific tab in the bar. When you do this, the UITabBarController retrieves the UIViewControllerassociated with that tab and presents its view as the current visible content in your UITabBarController.

Hope it helps.