disable all UITabBarItems on launch of iPhone application
self.window.rootViewController = self.tabBarController;
[self.window makeKeyAndVisible];

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    defaultImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Default.png"]]; // enter name of image with your company logo
    defaultImageView.frame =self.window.bounds;

    [self.window addSubview:defaultImageView];


    [self.window makeKeyAndVisible];

    [self continueLoading]; //Load what do you want to load


    return YES;
}

- (void) removeImageFromScreen
{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDelegate:defaultImageView];
    [UIView setAnimationDidStopSelector:@selector(removeFromSuperview)];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
    [UIView setAnimationDuration:0.3f];
    defaultImageView.alpha = 0;
    [UIView commitAnimations];
}