iOS Application launch black screen, UINavigationController, Nib, RootViewController

问题

I've got the following app, whose RootViewController is named TopicsViewController.

When I run it, there aren't any errors or breaks but the screen is black. No table, populated or empty, just a black screen. Not sure which of the following is happening:

• Is there something wrong with my application didFinishLaunchingWithOptions method in relation to a parser initlizing in it?
• Is it something to do with my nib file for the TopicsViewController?

I can show more code from my TopicsViewController class if needed.

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

***initializing code for parser which populates TopicsViewController (not shown to save space)*****

///////////////////////////////////////////
UIViewController *rootController =
[[TopicsViewController alloc]
 initWithNibName:@"TopicsViewController" bundle:nil];

navController = [[UINavigationController alloc]
                 initWithRootViewController:rootController];

self.window = [[UIWindow alloc]
               initWithFrame:[[UIScreen mainScreen] bounds]];
[self.window addSubview:navController.view];
[self.window makeKeyAndVisible];
return YES; 
}

回答1:

Instead of:

[self.window addSubview:navController.view];

Write:

self.window.rootViewController = self.navController;

来源：https://stackoverflow.com/questions/14487024/ios-application-launch-black-screen-uinavigationcontroller-nib-rootviewcontro