How to know if a user has changed tab?

Question

I have a Tab Bar Controller which has some Navigation Controllers as children. Is it possible to find out when a user navigated away from certain Navigation Controller (as he switched to another tab) in form of a callback?

Answer 1

Whichever class is the Tab Bar Controller's delegate will get sent the following selectors:

- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController