Initialization for ViewController under NavController in TabBarController - iphone

Question

I have the relatively common setup of a TabBarController whose tabs contain NavigationControllers which have TableViewControllers as their roots. I'm trying to perform some logic on initialization of one of these TableViewControllers but can't seem to find what init function gets called.
My goal is to add a listener in the TableViewController (that I have subclassed) which can respond to events by updating the navigationController.tabBarItem.badgeVluew property.
I've tried putting code into initWithStyle: as well as init but neither of them end up getting called. I've also tried putting it in viewDidLoad, but that only gets called once the controller actually appears (I need to have it happen as soon as the controller is loaded / as soon as the tab bar item shows up).
Does anyone know where I would put this code for it to happen on initialization of the controller?
Also, this is all set up through interface builder / NIBs. I'm not adding the nav controller or tableviewcontroller manually, which is why it's not clear what init function I need to override.

Answer 1

If you select one of your UITabBarItems in IB, you will see 'View loaded from "YourView"'. Click into this "gray" View. In the Inspector window you will see in the Attributes Tab (the tab on the left) the title and the NIB name which will be loaded (lets call it "YourNibName").
Now select the right tab of the inspector (Identity) and change the Classname (Combo next to Class) to your "YourViewController" class, which you must create in xcode. Don't use the standard ViewController, which is already selected. The InterfaceBuilder loads your nib and attaches it to your ViewController.
Open YourNibName and change FilesOwner's Class (Inspector, right Tab) to "YourViewController", too.
Your TabBar's NIB contains a FilesOwner, too. Create a ViewController for this FilesOwner and set its Class to this Controller (i.e. TabBarController)
In "TabBarController" you can find out which Tab was selected by using this code:
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController{
if ([viewController.nibName isEqualToString:#"NIBName1"]){
// Do something here, if you like. (i.e. Save the state in a string or int)
}
if ([viewController.nibName isEqualToString:#"NIBNAme2"]){
// Do something here, if you like. (i.e. Save the state in a string or int)
}
...
}
Here you can do something "global" or preinitialize something. This is ONE thing you can do.
INIT OF YOUR VIEWS:
If you select a Tab and the view (which is handled by YourViewController) will be shown for the first time, "viewDidLoad" will be called in "YourViewController"
- (void)viewDidLoad {
// Here you can add views programatically
[self.view addSubview:myNavigationController.view];
[self.view bringSubviewToFront:myNavigationController.view];
// And if you like, do some INIT here
[super viewDidLoad];
}
I hope this is what your question was about.
Now something about the badge. It's a hack, but works fine for me.
Header file:
Add an outlet to your controller, which is representing your TabBarController:
#interface yourController : UIViewController <UITabBarControllerDelegate> {
UITabBarController *tabBarController;
}
#property (nonatomic, retain) IBOutlet UITabBarController *tabBarController;
#end
Connect this outlet in IB with your TabBar.
Implementation:
In your TabBarControllerClass you can overwrite 'initWithNibName':
#synthesize tabBarController;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {
// Do some init here
// select your desired item (it will be loaded)
// then you can assign the badge
tabBarController.selectedIndex = 1;
tabBarController.selectedViewController.tabBarItem.badgeValue = #"222";
// and select the item you will start with
tabBarController.selectedIndex = 0;
// if you like you can add a notification, which you can activate from anywhere else
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(itemBadgeChanged:)
name:#"itemBadgeChangedNotification"
object:nil];
}
return self;
}
if you don't use nib, use '- (void)loadView { ... }' instead.
You are using a subclass of the TabBar controller, maybe you can use 'self.selectedIndex = 1;' instead of 'tabBarController.selectedIndex = 1;', and so on. Just try this out
Hope this helps!