如何以及在何处在 Swift 中初始化 UITabBarControllerDelegate？

Question

I have a UITabBarController linked to 4 UIViewController each embedded in a NavigationViewController .

I need to check if when one of these view controllers is currently selected, and the user clicks the same tab bar item for the same view, it will trigger an unwind segue action.

So I think I need to add a UITabBarControllerDelegate but when I tried to add it to the UITabBarController class in the viewDidLoad() method:

let tabBarDel: UITabBarControllerDelegate = UITabBarControllerDelegate()

I see the following error: ' UITabBarControllerDelegate ' cannot be constructed because it has no accessible initializers .

Answer 1

I extended the view controller class with UITabBarControllerDelegate. In the viewDidLoad() method I used self.tabBarController?.delegate = self

Answer 2

UITabBarController is a protocol, not a class. You can't instantiate a protocol. You need to create your own implementation of the protocol.