每次从标签栏按下标签时，如何执行方法？

Question

I want to run a method every time a tab from the tab bar is pressed in my app. How do I do this? I have a tab bar controller in my storyboard (built when i chose tab bar application when I created the project).

For example I want to print 'tab button pressed to the console every time a tab button is pressed.

I tried adding this in the app delegate without any luck:

- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item{

    NSLog(@"Tab Button Pressed");

}

This is probably quite simple but I'm missing something.

Answer 1

您是否已将视图控制器设置为选项卡栏的委托？

Answer 2

If you are using xcode 4.2.x then the templates set up the UITabBarController in code in the appDelegate

self.tabBarController = [[[UITabBarController alloc] init] autorelease];
self.tabBarController.delegate = self;    //<---- Add this line
self.tabBarController.viewControllers = [NSArray arrayWithObjects:viewController1, viewController2, nil];
self.window.rootViewController = self.tabBarController;

If you have an old style project or built your structure using interface builder then:

1. Right click the Tab bar controller in the objects view
2. Locate the delegate outlet
3. Connect the delegate outlet to the File's Owner