Objective-C Thread 1:Program received signal: "SIGABRT"

I have an error in this line.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    [self.window addSubview:_viewController.view];
    [self.window makeKeyAndVisible];
    return YES;
}

I'm using Xcode 4.1 and reading Appress Book "Begin开发者_运维技巧ning iPhone 4 Development" Chapter 4.

Regards, Herman

Check your IBOutlets. Look if they are all connected and if you see any outlets with an ! on the right side then delete that outlet, that means that you have connected an outlet earlier, and have deleted it in your header afterwards. That causes a SIGABRT crash. Check the same thing for IBActions.