How do I set up a Tab Bar Controller within an existing Navigation Controller? - uinavigationcontroller

Question

I'm pretty new to iOS. I'm building an app and am running into an issue. I have a navigation controller with a table view controller atop its stack. When I select a row in that table view controller, what I'd like to see is a collection view with the following:
The nav bar with the name that appears on the selected cell as the navigation item title.
A collection view as the main interface
a tab bar with the collection view, and an imagePickerController
Here's what my code looks like:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NewTabBarController *tbc = [[NewTabBarController alloc] init];
UIImagePickerController *takeAPicture = [[UIImagePickerController alloc] init];
UITabBarItem *tabItem = [takeAPicture tabBarItem];
[tabItem setImage:[UIImage imageWithContentsOfFile:#"CameraIcon.jpg"]];
[tabItem setTitle:#"Take a photo!"];
UICollectionViewFlowLayout *photoFlow = [[UICollectionViewFlowLayout alloc] init];
PhotoCollectionViewController *photoHub = [[PhotoCollectionViewController alloc] initWithCollectionViewLayout:photoFlow];
[tbc setViewControllers:[NSArray arrayWithObjects:photoHub, takeAPicture, nil]];
NSArray *items = [[items accessor] allItems];
Item *item = [items objectAtIndex:[indexPath row]];
[photoHub setItem:item];
[photoHub useLayoutToLayoutNavigationTransitions];
[[self navigationController] pushViewController:tbc animated:YES];
}
Then in my PhotoCollectionViewController implementation I have:
#syntesize item;
- (void)viewDidLoad {
[super viewDidLoad];
UINavigationItem *itemHeader = [self navigationItem];
[itemHeader setTitle:[item itemName]];
UITabBarItem *tabItem = [self tabBarItem];
[tabItem setImage:[UIImage imageWithContentsOfFile:#"itemImage.jpg"]];
[tabItem setTitle:[NSString stringWithFormat:#"Photos of %#", [item itemName]]];
}
My problem is that when I select the cell, The collection view loads, and I can see the cells I have set up in the collection view, but the nav bar item has no title, and the tab bar item has "Photos of (null)" and no image. The "Take a photo!" text appears, but the image does not.
Do you guys have any idea how I can restructure this to make everything flow correctly. I must be doing something wrong in the way I'm utilizing tab and nav controllers.I don't want there to be any tabs until this stage in the app, which is 3 or 4 VCs in already. Should I be using a tab bar controller from the App Delegate onward?

Answer 1

The problem here is that you are pushing tab bar controller onto a navigation controller stack. The view controllers of a tab bar will have a navigation item, but their navigation items aren't shown when the view controller is on screen. Instead, the tab bar controller's navigation item is on screen.
You could use self.tabBarController.navigationItem, but then each view controller will have to modify the navigation item every time it's brought on/off screen, which is really messy.
If you're going to use a UITabBarController, I would recommend either presenting it modally, or having it be the root view controller on your UIWindow. It's tough to get it working right as a view controller in a navigation controller's view controller stack.
Your tab bar item not showing its name is a separate issue. It's because viewDidLoad is getting called before you set your item instance, specifically it's getting called when you call [tbc setViewControllers:[NSArray arrayWithObjects:photoHub, takeAPicture, nil]];
You can confirm this by breakpointing in view did load, where you'll see that item is nil. If you haven't already, you should overload your setItem: method in PhotoCollectionViewController, and have that method also update your UI.