尝试显示其视图不在Windows层次结构中的ViewController [英] Attempt to present ViewController whose view is not in the windows hierarchy

问题描述

我遇到一个奇怪的问题：我制作了两个视图控制器，我可以用代码切换视图：

I meet a strange problem: I made 2 view controllers for wich I can switch the view with code:

var currentViewController:UIViewController=UIApplication.shared.keyWindow!.rootViewController!

func showController()
{
    let ViewControllernew1 = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "viewController2")

    currentViewController.present(ViewControllernew1, animated: true, completion: nil)

}

我的应用程序正确打开到第一个视图控制器，然后，当我点击精灵工具包场景中创建的按钮时，我可以成功地将视图切换到我的新视图控制器（我的第二个场景成功显示）但是，在此切换后，我无法再更改我的视图控制器。如果我再次单击该按钮，我会收到以下消息：

My app open correctly to the first view controller, then, when I click on the button created on a sprite kit scene, I can switch the view to my new view controller successfully (I get my second scene successfully showed) but then, I can not change anymore my view controller after this switch. If I click again on the button, I get this message:

尝试在Test_Vuforia.GameViewController上显示：0x12f549610，其视图不在窗口层次结构中！

Attempt to present on Test_Vuforia.GameViewController: 0x12f549610 whose view is not in the window hierarchy!

你知道这是什么问题吗？我知道我处于根位，所以在切换之后我不能再改变我的视图控制器，但是如何更改它？

Do you know what is the problem ? I understand I'm in the root position so that I can not change anymore my view controller after having switched it, but how to change that ?

谢谢！

编辑：

我的代码在SKScene中使用，而不是来自UIVewController，我在使用时遇到此错误后缀自我。 ：View类型的值（SKScene）没有成员'present'。

My code is used inside a SKScene and not from a UIVewController and I get this error when I use the suffix self. : Value of type View (SKScene) has no member 'present'.

我正在用Vuforia创建一个增强现实游戏，我需要用SKScene切换AR视图。

I'm creating an augmented reality game with Vuforia and I need to switch AR view with SKScene.

推荐答案

问题

当前viewController不是 rootViewController 来自 UIApplication 。所以你应该找到当前可见的viewController，然后从那里显示它。

Issue

Current viewController is not the rootViewController from UIApplication. So you should find the current viewController which is visible and then present it from there.

只需查找你的 UIApplication Stack 上的topViewController，并从那里出现你的控制器。

Simply find the topViewController on your UIApplication Stack, and from there present your controller.

let newViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "viewController2")
UIApplication.topViewController()?.present(newViewController, animated: true, completion: nil)

UIApplication 的扩展为您的案例派上用场

This extension of UIApplication comes in handy for your case

extension UIApplication {
    class func topViewController(base: UIViewController? = UIApplication.sharedApplication().keyWindow?.rootViewController) -> UIViewController? {
        if let nav = base as? UINavigationController {
            return topViewController(base: nav.visibleViewController)
        }
        if let tab = base as? UITabBarController {
            if let selected = tab.selectedViewController {
                return topViewController(base: selected)
            }
        }
        if let presented = base?.presentedViewController {
            return topViewController(base: presented)
        }
        return base
    }
}

参考文献： Zammbi

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