Question

I’m playing with some sample code to try and figure out once and for all how to make navigation controller (s) and a tab controller to work together. As a bonus without memory leaks.

Having problems as shown below…

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:
        (NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] 
        bounds]] autorelease];

    // Override point for customization after application launch.
    UIViewController *viewController1 = [[[FirstViewController alloc] 
            initWithNibName:@"FirstViewController" bundle:nil] autorelease];
    UIViewController *viewController2 = [[[SecondViewController alloc] 
            initWithNibName:@"SecondViewController" bundle:nil] autorelease];

    self.tabBarController = [[[UITabBarController alloc] init] autorelease];
    self.tabBarController.viewControllers = [NSArray arrayWithObjects:
         viewController1, viewController2, nil];
    self.window.rootViewController = self.tabBarController;
    self.navigationController = [[UINavigationController alloc] 
         initWithRootViewController:self.tabBarController]; <<<<

    [self.window makeKeyAndVisible];
    return YES;

In my main project I have an outlet for 4 different navigation controllers and I call each like so.

MyAppDelegate *delegate = (MyAppDelegate *)[[UIApplication sharedApplication] 
      delegate];
[delegate.balNavController pushViewController:nextController animated:YES];

But this leaks and is causing problems.

Without using the interface builder, can someone advise me, in simple terms how I should be doing this, perhaps with a few lines of code.

Answer 1

I strongly encourage your to pick up a copy of the Big Nerd Ranch Guide to iPhone Programming. It has excellent exposition and examples to get you proficient in the basics. Now on to your issues…

A UITabBarController is set by giving it an NSArray of UIViewControllers or even UINavigationControllers. The Tab Bar doesn’t mind which.

A UINavigationController is set by giving it a UIViewController that will be the root.

Keep in mind that the Tab Bar is not a View Controller, so it cannot be the root of a Navigation Controller!

Combining these is simply a matter of correct order. Here’s a generic example that hopefully illustrates this.

- (BOOL)application:(UIApplication *)application 
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{   
    // UIViewController with UINavigationBar
    UIViewController *firstViewController = [[UIViewController alloc] init];
    UINavigationController *firstNavController = [[UINavigationController alloc] initWithRootViewController:firstViewController];

    // Custom subclass of UIViewController with UINavigationBar
    CustomViewController *secondViewController = [[CustomViewController alloc] init];
    UINavigationController *secondNavController = [[UINavigationController alloc] initWithRootViewController:secondViewController];

    // UIViewController without UINavigationBar
    UIViewController *thirdViewController = [[UIViewController alloc] init];

    // Set the NSArray of ViewControllers
    NSArray *viewControllers = [NSArray arrayWithObjects:firstNavController, secondNavController, thirdViewController, nil];
    // This array retains the controllers, so go ahead and release them now
    [firstNavController release]; 
    [secondNavController release]; 
    [thirdViewController release]; 

    // Set up the UITabBarController -  It now holds everything
    tabBarController = [[UITabBarController alloc] init];
    [tabBarController setViewControllers:viewControllers];

    // Add the Tab Bar Controller to the window.
    [window addSubview:[tabBarController view]];
    [window makeKeyAndVisible];

    return YES;
}