Question

The structure is as follows:

• View
• Tab Bar Controller
  • Navigation Controller
    • View Controller
  • Navigation Controller
    • View Controller
  • Navigation Controller
    • View Controller
  • Navigation Controller
    • View Controller
  • Navigation Controller
    • View Controller
  • Navigation Controller
    • View Controller

The above controllers have been initialised in interface builder.

What I’m trying to do is add a right UIBarButtonItem to each navigation controller but not having any success.

Here’s what I’ve tried:

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.view.backgroundColor = [UIColor clearColor];
    self.view.opaque = NO;
    self.tabBarController.view.frame = self.view.bounds;

    NSArray *currentViewControllers = self.tabBarController.viewControllers;
    NSMutableArray *updatedViewControllers = [NSMutableArray array];

    for (int i=0; i<currentViewControllers.count; i++) {
        UINavigationController *tempNav = [[UINavigationController alloc]init];
        tempNav = [currentViewControllers objectAtIndex:i];
        UIBarButtonItem *dismissButton = [[UIBarButtonItem alloc] 
                                          initWithTitle:@"Done"                                            
                                          style:UIBarButtonItemStyleBordered 
                                          target:self 
                                          action:@selector(dismissLibraryBrowser)];
        tempNav.navigationItem.rightBarButtonItem = dismissButton;
        [updatedViewControllers addObject:tempNav];
        [dismissButton release];
        [tempNav release];

        NSLog(@"Added controller number %d",i);
    }

    self.tabBarController.viewControllers = [NSArray arrayWithArray:updatedViewControllers];

    [self.view addSubview:tabBarController.view];
}

The code executes without any errors, but the button doesn’t appear. I’m sure I’ve misunderstood something here. Would appreciate some guidance.

Answer 1

You are over complicating things slightly with recreating viewControllers and temporary arrays. You just need to manipulate the objects loaded from the nib

[self.tabBarController.viewControllers enumerateObjectsUsingBlock:^(UINavigationController *navigationController, NSUInteger idx, BOOL *stop) {

    UIViewController *rootViewController = [navigationController.viewControllers objectAtIndex:0];

    UIBarButtonItem *rightBarButtonItem  = 
      [[UIBarButtonItem alloc] initWithTitle:@"Done"                                            
                                       style:UIBarButtonItemStyleBordered 
                                      target:self 
                                      action:@selector(dismissLibraryBrowser)];

    rootViewController.navigationItem.rightBarButtonItem = rightBarButtonItem;

 }];

---

As for the structure of your app – the docs for UITabBarController say

When deploying a tab bar interface, you must install this view as the root of your window. Unlike other view controllers, a tab bar interface should never be installed as a child of another view controller.

So I would suggest having a look at restructuring some stuff, if you need it only occasionally why not consider presenting it modally?