The different of the class name that having **Delegate** and haven't have **Delegate** in iOS API

In iOS API, we can see UITabBarItem Class Reference and UITabBarDelegate Protocol Reference... when we search for the keyword "tabbar", I want to as开发者_C百科k what is the different between the class name having Delegate and haven't have Delegate?

Thanks

UITabBarDelegate isn't a class, its protocol - declaration which function contains class, that adopts this protocol. There is speсial property in class UITabBarItem named delegate, by which it can refer to an object of this class with protocol and execute methods of the protocol

They are just names.

These are Classes - You have the UITabBarController (controller for the view) The UITabBarView (what is displayed on the screen)

This is a Protocol - The UITabBarDelegate (an object that responds to events, usually also the controller)

The "Delegate" name is just a convention that is used by Apple to indicate its role (for example, AppDelegate is another one).

Unfortunately, I cannot really answer more than that beyond the scope of iOS development. You need to understand the difference between Class and Delegate; in that case, this post should be moved to Programmers.