Show Multiple views using custom tabs within UiViewController

Show Multiple views using custom tabs

   - (id)initWithNibName:(NSString *)nibNameOrNil 
               bundle:(NSBundle *)nibBundleOrNil
    {
    AccountViewController *accountViewController = [[AccountViewController alloc]
                        initWithNibName:@"AccountViewController" bundle:nil];
    MoreViewController *moreViewController = [[MoreViewController alloc]
                        initWithNibName:@"MoreViewController" bundle:nil];
    BarTabViewController *barTabViewController = [[BarTabViewController alloc]
                        initWithNibName:@"BarTabViewController" bundle:nil];
    LocationsViewController *locationsViewController = [[LocationsViewController alloc]
                        initWithNibName:@"LocationsViewController" bundle:nil];

    self.viewControllers = [NSArray arrayWithObjects:locationsViewController, accountViewController,
                            barTabViewController, moreViewController, nil];

    [self.view addSubview:locationsViewController.view];
    self.selectedController = locationsViewController;
    self.tabBarController = [[UITabBarController alloc] init];
self.tabBarController.selectedIndex = 0;

self.tabBarController.viewControllers = [NSArray arrayWithObjects:locationsViewController, accountViewController,
                    barTabViewController, moreViewController, nil];
self.tabBarController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self.navigationController pushViewController:delegate.tabBarController animated:YES];
        return self;
    }

Like I said, this will display the selected controller properly, however when the app launches and I try to switch views with the tab bar, the subview just become grey... The following is the code to switch items:

- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item
{
    if (item == locationsTabBarItem) {
        UIViewController *locationsController = [viewControllers objectAtIndex:0];
        [self.selectedController.view removeFromSuperview];
        [self.view addSubview:locationsController.view];
        self.selectedController = locationsController;
    }
    else if (item == accountsTabBarItem) {
        UIViewController *accountsController = [viewControllers objectAtIndex:1];
        [self.selectedController.view removeFromSuperview];
        [self.view addSubview:accountsController.view];
        self.selectedController = accountsController;
    }
    else if (item == barTabTabBarItem) {
        UIViewController *barTabController = [viewControllers objectAtIndex:2];
        [self.selectedController.view removeFromSuperview];
        [self.view addSubview:barTabController.view];
        self.selectedController = barTabController;
    }
    else {
        UIViewController *moreController = [viewControllers objectAtIndex:3];
        [self.selectedController.view removeFromSuperview];
        [self.view addSubview:moreController.view];
        self.selectedController = moreController;
    }
}