But it is very well documented on iOS docs As the user interacts with a tab bar interface, the tab bar controller object sends notifications about the interactions to its delegate. The delegate can be any object you specify but must conform to the UITabBarControllerDelegate protocol. You can use the delegate to prevent specific tab bar items from being selected and to perform additional tasks when tabs are selected. You can also use the delegate to monitor changes to the tab bar that are made by the More navigation controller, which is described in more detail in The More navigation controller. taken from https://developer.apple.com/documentation/uikit/uitabbarcontroller is this doc also going to be updated?