Getting the selectedIndex of the currently selected tab from a viewcontroller

Question

I currently have an iPhone application with a tabbar and multiple viewcontrollers. All the views are designed in Interface Builder. I'd like to be able to get the currently selected index of the tabbar from the viewcontroller, but for some reason this property returns (null).

I called the following in the viewDidLoad function of my viewcontroller:

self.tabBarController.selectedIndex

What would be the correct way to do this?

Updated with the code of the AppDelegate class.

MyAppDelegate.h

#import <UIKit/UIKit.h>

@interface MyAppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate> {
  UIWindow *window;
  UITabBarController *tabBarController;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet UITabBarController *tabBarController;

@end

MyAppDelegate.m:

#import "MyAppDelegate.h"

@implementation MyAppDelegate

@synthesize window, tabBarController;

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

- (void)dealloc {
    [tabBarController release];
    [window release];
    [super dealloc];
}

@end

Answer 1

You should have a pointer to your tabbar in your appDelegate class. Your view has no tabbar, so you recieve nil from [self.tabBarController selectedIndex].

Answer 2

I think I've got it. Using the following returns the correct index:

  MyAppDelegate *appDelegate = (MyAppDelegate *)[[UIApplication sharedApplication] delegate];
NSLog(@"%d", appDelegate.tabBarController.selectedIndex);

The reason the application was crashing was the fact that I used %@ instead of %d in the NSLog part. I could have sworn I tried %d before, strange...

The index is now returned, but only once. After you tap the tab section an index number is returned, but when you tap another section again no number is printed. Probably because the view has already been loaded once. Is there any way to work around this?