tabBarController：shouldSelectViewController：设置委托时不调用

Question

I think I've done my homework here.

I want my app delegate to be the delegate for my UITabBarController .

Using IB, I've connected UITabBarController 's delegate to my Application Delegate.

App Delegate Header file is:

@interface MyAppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate> {

The delegate method I'm trying to implement is:

-(BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController {
    NSLog(@"shouldSelectViewController called.");
    // do some stuff with viewController
    return YES;
}

My app delegate has an outlet to the UITabBarController that's connected in IB. When I do this:

NSLog(@"tab bar controller delegate is %@", self.tabBarController.delegate);

I get a good result such as tab bar controller delegate is <MyAppDelegate: 0x6e86a30> .

What am I missing?

Answer 1

Just write this code. Usually in viewDidLoad() .

self.tabBarController.delegate = self;

If the current controller is a UITabBarController then:

self.delegate = self

Answer 2

Ok, found the solution. I had some old code in my RootViewController that set up this controller as the delegate. No delegate methods were implemented on the RootViewController , so it appeared as if nothing was happening. Because the RootViewController is set as delegate AFTER MyAppDelegate , the delegate was actually set to the RootViewController .

So the lesson is double-check your code to make sure some other object isn't also being set as the delegate.