试图提出VC，其观点是不是在窗口层次

我想在线程中打开文件，这里是我的代码：试图提出VC，其观点是不是在窗口层次

DispatchQueue.main.async(execute: {() -> Void in 
    var documentsURL = (FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)).appendPathComponent(“File.pdf") 
    self.docController = UIDocumentInteractionController.init(url: documentsURL as URL) 
    self.docController?.delegate = self as? UIDocumentInteractionControllerDelegate 
    self.docController?.presentPreview(animated: true) 
    self.docController?.presentOpenInMenu(from: CGRect.zero, in: self.view, animated: true) 
})

时，主屏幕显示移动此警告和文件无法打开

Warning: Attempt to present <_UIDocumentActivityViewController: 0x...> on <HCM.PrintVacationDecisionVC: 0x...> whose view is not in the window hierarchy!

任何有助于解决这个问题？

来源

2017-07-27 Aya Aboud

'PrintVacationDecisionVC'是不可见的，所以它不能呈现'UIDocumentInteractionController'。 – Larme

链接没有解决我的问题，我做了很长的搜索之前发布问题 –

添加电子邮件xtention给予您的应用程序的波纹管，并在任何想要呈现任何视图控制器的地方使用它，它对我有用，希望它对您有所帮助。

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

，并按照代码目前它：

UIApplication.topViewController()?.present(vc, animated: true, completion: nil)

来源

2017-07-27 10:32:24

如果您试图在viewDidLoad方法中呈现模态视图控制器，可尝试将此调用移至viewDidAppear：方法。

来源

2017-07-27 10:20:58

你需要找到顶部视图控制器

从

https://stackoverflow.com/a/26859650/4601900

extension UIViewController { 
func topMostViewController() -> UIViewController { 
    // Handling Modal views 
    if let presentedViewController = self.presentedViewController { 
     return presentedViewController.topMostViewController() 
    } 
    // Handling UIViewController's added as subviews to some other views. 
    else { 
     for view in self.view.subviews 
     { 
      // Key property which most of us are unaware of/rarely use. 
      if let subViewController = view.nextResponder() { 
       if subViewController is UIViewController { 
        let viewController = subViewController as UIViewController 
        return viewController.topMostViewController() 
       } 
      } 
     } 
     return self 
    } 
} 
} 

extension UITabBarController { 
override func topMostViewController() -> UIViewController { 
    return self.selectedViewController!.topMostViewController() 
} 
} 

extension UINavigationController { 
override func topMostViewController() -> UIViewController { 
    return self.visibleViewController.topMostViewController() 
}

}

如何使用

UIApplication.sharedApplication().keyWindow!.rootViewController!.topMostViewController()

来源

2017-07-27 10:23:02

当我尝试使用的代码有错误的行窗口（类型vc没有成员窗口）和getCurrentViewController undefined –

你尝试使用AppDelegate的窗口？ –

您是不是要找使用的AppDelegate，而不是自我 –

试图提出VC，其观点是不是在窗口层次

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