刚开始使用Xcode 4.5,我在控制台得到了这个错误:

警告:试图在< ViewController: 0x1ec3e000>上显示< finishViewController: 0x1e56e0a0 >,其视图不在窗口层次结构中!

视图仍在显示,应用程序中的一切都在正常工作。这是iOS 6的新功能吗?

这是我用来在视图之间更改的代码:

UIStoryboard *storyboard = self.storyboard;
finishViewController *finished = 
[storyboard instantiateViewControllerWithIdentifier:@"finishViewController"];

[self presentViewController:finished animated:NO completion:NULL];

当前回答

    let alert = UIAlertController(title: "", message: "YOU SUCCESSFULLY\nCREATED A NEW\nALERT CONTROLLER", preferredStyle: .alert)
    func okAlert(alert: UIAlertAction!)
    {
        
    }
    alert.addAction(UIAlertAction(title: "OK", style: .default, handler: okAlert))
    
    let scenes = UIApplication.shared.connectedScenes
    let windowScene = scenes.first as? UIWindowScene
    let window = windowScene?.windows.first
    var rootVC = window?.rootViewController
    
    if var topController = rootVC
    {
        while let presentedViewController = topController.presentedViewController
        {
            topController = presentedViewController
        }
        rootVC = topController
    }
    rootVC?.present(alert, animated: true, completion: nil)

其他回答

我通过将start()函数移动到解散完成块内部来修复它:

self.tabBarController.dismiss(animated: false) {
  self.start()
}

Start包含对self.present()的两个调用,一个用于UINavigationController,另一个用于UIImagePickerController。

这为我解决了问题。

我在Swift 4.2上也有类似的问题,但我的观点没有从视图周期中呈现出来。我发现我有多个segue要同时呈现。所以我使用dispatchAsyncAfter。

func updateView() {

 DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in

// for programmatically presenting view controller 
// present(viewController, animated: true, completion: nil)

//For Story board segue. you will also have to setup prepare segue for this to work. 
 self?.performSegue(withIdentifier: "Identifier", sender: nil)
  }
}

我的问题是,在我调用窗口上的makeKeyAndVisible()之前,我在UIApplicationDelegate的didFinishLaunchingWithOptions方法中执行segue。

我也有同样的问题。我必须嵌入一个导航控制器,并通过它呈现控制器。下面是示例代码。

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    UIImagePickerController *cameraView = [[UIImagePickerController alloc]init];
    [cameraView setSourceType:UIImagePickerControllerSourceTypeCamera];
    [cameraView setShowsCameraControls:NO];

    UIView *cameraOverlay = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 768, 1024)];
    UIImageView *imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"someImage"]];
    [imageView setFrame:CGRectMake(0, 0, 768, 1024)];
    [cameraOverlay addSubview:imageView];

    [cameraView setCameraOverlayView:imageView];

    [self.navigationController presentViewController:cameraView animated:NO completion:nil];
//    [self presentViewController:cameraView animated:NO completion:nil]; //this will cause view is not in the window hierarchy error

}

当我试图在viewDidLoad中呈现一个UIViewController时,我也遇到了这个问题。James Bedford的答案是可行的,但我的应用程序先显示了1到2秒的背景。

经过一些研究,我找到了一种方法来解决这个使用addChildViewController。

- (void)viewDidLoad
{
    ...
    [self.view addSubview: navigationViewController.view];
    [self addChildViewController: navigationViewController];
    ...
}