我升级到iOS9，开始出现这个错误。我能够修复它，但添加以下代码到- (BOOL)应用程序:(UIApplication *)应用程序didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

NSArray *windows = [[UIApplication sharedApplication] windows];
for(UIWindow *window in windows) {
    if(window.rootViewController == nil){
        UIViewController* vc = [[UIViewController alloc]initWithNibName:nil bundle:nil];
        window.rootViewController = vc;
    }
}

OrdoDei给出了一个正确而有价值的答案。我添加这个答案只是为了给出一个didFinishLaunchingWithOptions方法的例子，该方法使用了他的答案以及其他关于导航控制器的评论。

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

    // Override point for customization after application launch.

    // Instantiate the main menu view controller (UITableView with menu items).
    // Pass that view controller to the nav controller as the root of the nav stack.
    // This nav stack drives our *entire* app.
    UIViewController *viewController = [[XMMainMenuTableViewController alloc] init];
    self.navigationController = [[UINavigationController alloc] initWithRootViewController:viewController];

    // Instantiate the app's window. Then get the nav controller's view into that window, and onto the screen.
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // [self.window addSubview:self.navigationController.view];
    // The disabled line above was replaced by line below. Fixed Apple's complaint in log: Application windows are expected to have a root view controller at the end of application launch
    [self.window setRootViewController:self.navigationController];
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}

虽然很多答案看起来都是正确的，但没有一个能帮我解决问题。我正在尝试使用空的应用程序模板，并试图为了理解而直接加载到.xib文件(就像旧的窗口模板)。苹果似乎在运行NSLog消息。

我使用的是Xcode 4.3，似乎没有任何东西可以消除这条消息，我想知道为什么。最后，我决定在Xcode 4.5(预览版/iPhone 6.0版本)中看看会发生什么，这条消息不再存在。在移动。

以上建议没有一个能解决我的问题。我的回答是:

Add:

window.rootViewController = navigationController;

后:

[window addSubview:navigationController.view];

在我的appdelegate中

- (void)applicationDidFinishLaunching:(UIApplication *)application {

在AppDelegate中替换

 [window addSubview:[someController view]];

to

  [self.window setRootViewController:someController];

没有一个答案能完全解决我的问题。

我正在开发一个升级到ARC的旧iOS4项目，现在正在为iOS 7开发Xcode 5

我通读了所有这些文件，并开始检查我的配置和代码。

为我修复它的是添加

-(BOOL) application:(UIApplication*) application didFinishLaunchingWithOptions: (NSDictionary*) launchOptions
{
    // Maybe do something
    return YES;
}

除了有

- (void)applicationDidFinishLaunching:(UIApplication *)application
{
}

我没有

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

在得到错误之前。