Applications are expected to have a root view controller at the end of application launch

Solution 1:

Replace in AppDelegate

 [window addSubview:[someController view]];

to

  [self.window setRootViewController:someController];

Solution 2:

I had this same problem. Check your main.m. The last argument should be set to the name of the class that implements the UIApplicationDelegate protocol.

retVal = UIApplicationMain(argc, argv, nil, @"AppDelegate");

Solution 3:

I had the same error when trying to change the first view controller that was loaded in

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

At first I didn't really know where the error was coming from precisely so I narrowed it down and found out what went wrong. It turns out that I was trying to change the display of a view before it actually came on screen. The solution was hence to move this code in the viewcontroller that was giving me trouble from

- (void)viewDidLoad

to

- (void)viewDidAppear:(BOOL)animated

and the error stopped appearing. My problem specifically was caused by making a UIAlertView show.

In your case I suggest you check out the code in the tabBarController's active view controller (as it is probably a problem in that view controller). If that doesn't work, try to set the starting settings in the nib file instead of in code - or if you want to do it in code, try moving the code to the tabBarController's active viewcontroller's appropriate method.

Good luck!

Solution 4:

I got this when starting with the "Empty Application" template and then manually adding a XIB. I solved it by setting the main Nib name as suggested by Sunny. The missing step in this scenario is removing

self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

from

application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

As it will overwrite the instance of your window created in the Xib file. This is assuming you have created a ViewController and wired it up with your window and App Delegate in the XIB file as well.

Solution 5:

This happened to me. Solved by editing .plist file. Specify the Main nib file base name.(Should be MainWindow.xib). Hope this will help.