how to get the event that switch tab menu on iphone

I'm trying to figure out how to catch the event that controls the switch tabs on the 开发者_运维知识库UITabBarController. How could I accomplish this?

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Implement UITabBarControllerDelegate e.g. in your app delegate's applicationDidFinishLaunching

- (void)applicationDidFinishLaunching:(UIApplication *)application
{
    tabBarController.delegate = self;
    [window addSubview:tabBarController.view];
}

Then implement either:

- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController;

- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController;

The first method is called before the view switch and gives you a chance to 'veto' the view switch by returning NO

The second method is called after the view switch has taken place

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If you are using storyboard, do this

in didFinishLaunchingWithOptions

UITabBarController *tabBar = (UITabBarController *)self.window.rootViewController;
[tabBar setDelegate:self];

Also in AppDelegate, keep <UITabBarControllerDelegate>

And then

-(void) tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{
   //Write your code here
}

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Have a look at the following method in UITabBarControllerDelegate:

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

Tells the delegate that the user selected an item in the tab bar.

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Better late than never. In case of swift 4 you can do it in the following way.

tabBarViewController.delegate = self

And implement UITabBarDelegate in your class. You will get the callback in

override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
  //Stuff to do
}

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Is UITabBarControllerDelegate what you're looking for, particularly -tabBarController:didSelectViewController:?