Question

I have a UIViewController and I wish to place a simple UITabBar like the in the screenshot below: I don’t want to use an UITabBarController. In fact, my original setup uses one, and it’s easy as cake to get it to work.

However, the thing is I found out it’s a bad idea to put UITabBarControllers inside Navigation Controllers, so I’m forced to refactor the hierarchy (so please don’t suggest using one).

Given an UIViewController, how can I add an UITabBar on the bottom programatically? I got my UITabBarDelegate all setup to show a specific view when 1 of the tab bars is clicked, but the problem is when the view controller loads, no tab bar shows up! Here’s my code to do that:

- (void) viewDidLoad {
        ...some initialization...
    CGRect frame = CGRectMake(0, 431, 320, 49);


    profileItem = [[UITabBarItem alloc] init];
    profileItem.image = icon;
    profileItem.title = @"Diet";    

    tabBar = [[UITabBar alloc] initWithFrame:frame];
    NSArray* items = [[NSArray alloc] initWithObjects:profileItem, nil];

    tabBar.items = items;
    tabBar.delegate = self;
    [tabBar setSelectedItem:[tabBar.items objectAtIndex:0]];

    [self.view addSubview:tabBar];
    [super viewDidLoad];
}

What am I missing here?

EDIT: Argh, I found out it has to do with the frame… Hmm.. what y-coordinate should I use if I have an existing navigation header on top?

Answer 1

You mention in your edit that you already determined that it has to do with the frame. Your problem may stem from the fact that your view’s size in viewDidLoad isn’t guaranteed to be the same is it will be when it eventually gets displayed. UIKit resizes the view to fit the context in which it’s being displayed just before viewWillAppear:.

If you want to add the tab bar in viewDidLoad, then you should position it at the bottom of your view’s frame by doing some math:

CGRect frame = CGRectMake(0, self.view.bounds.size.height - 49,
                          self.view.bounds.size.width, 49);

Then set an appropriate autoresizingMask so that it remains at the bottom even if UIKit resizes your view:

tabBar.autoresizingMask = UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleWidth;