在UITabBarController上选择选项卡时，如何显示ViewController？

Question

I have a UITabBarController with a profile tab. I want to present a login view controller if the profile tab is pressed, but the user is not logged in. If the user presses cancel, I want the tab bar controller to have the same tab selected as before.

Answer 1

You need to use UITabBarControllerDelegate

-tabBarController:shouldSelectViewController:

or

-tabBarController:didSelectViewController:

Detect your profile controller and present login controller.

https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITabBarControllerDelegate_Protocol/index.html#//apple_ref/occ/intf/UITabBarControllerDelegate