Question

After upgrading to Xcode 4.5 from 4.4, I ran the apps that I had made in v 4.4. Although the app compiles correctly, I see the following message in Output section of Debug area:

Application windows are expected to have a root view controller at the end of application launch.

Can somebody please tell me why do I see this message after upgrading? I went through some of the answers for similar question. But I have not found anything that tells me why I see this message after upgrading.

Thank you!

Edit 1:

Am I supposed to incorporate the code in AddDelegate.m. If yes, I did something similar while following a book.

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

    [[NSBundle mainBundle] loadNibNamed:@"TabBarController" owner:self options:nil] 
    [self.window addSubview:rootController.view];

    [self.window makeKeyAndVisible];
    return YES;
}

Answer 1

In iOS 3.x and below, you used to do this:

[window addSubview:tabBarController.view]

Since iOS 4, the canonical way is to do this:

window.rootViewController = tabBarController;

If you do not need to support iOS 2.x/3.x, then you should upgrade your code to do the latter.

IIRC, the warning’s existed since iOS 5. It depends on the iOS version you run on, not the Xcode version.