Delay in updating Tab Bar Item's Badge Value

Question

I have a function which runs every 5 seconds to check for new messages, if a new message is triggered I'm updating the badge value of the tab bar item using the below code

    NSString *chkUrl = @"http://domain.com/script.php";
    NSURL *url = [[[NSURL alloc] initWithString:chkUrl] autorelease];
    NSError *error = nil;
    NSStringEncoding encoding;
    NSString *returnHTML = [[NSString alloc] initWithContentsOfURL:url usedEncoding:&encoding error:&error];

    int totalNewMessages = [[returnHTML stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] intValue];
    AppDelegate *mainDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

    NSLog(@"badge before:%@",[[mainDelegate.tabBarController.viewControllers objectAtIndex:2] tabBarItem].badgeValue);
    [[mainDelegate.tabBarController.viewControllers objectAtIndex:2] tabBarItem].badgeValue = [NSString stringWithFormat:@"%d",totalNewMessages];
    NSLog(@"badge after:%@",[[mainDelegate.tabBarController.viewControllers objectAtIndex:2] tabBarItem].badgeValue);

The problem is the badge value is not updating immediately! Maybe in the third of fourth call it will be updated! Anything wrong I'm doing! Or is it a bug in iOS!

As a work around, I repeated the above line 10 times on every update, but again it's not updating, so the problem is a delay in updating the badge value, it's not a matter of re-run the update line!

BTW, this problem is taking place in both Xcode 4.6 Simulator & my iPhone 5 with iOS 6.1

Answer 1

I Found the problem :)

My function that was running every 5 seconds was inside the below code

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,
                                         (unsigned long)NULL), ^(void) {
    [self checkNewMessages];
});

When I changed it to the below, it worked like a charm!

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    dispatch_async(dispatch_get_main_queue(), ^{
        [self checkNewMessages];
    });
});