Attempt to present vc whose view is not in the win

Question

This question already has an answer here:

• Attempt to present * on * whose view is not in the window hierarchy 7 answers

I'm trying to open file in thread and here is my code:

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)
})

when move to main screen this warning is displayed and file not open

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

Any help to solve this problem?

Answer 1

Add extention given bellow to your application and use it any where you want to present any view controller, it works for me hope it helps you.

//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
    }
}

And Present it by following code:

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

Answer 2

If you are attempting to present a modal view controller within the viewDidLoad method, can try to move this call to the viewDidAppear: method.

Answer 3

You need to find top view controller

From

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()
}

}

How to use

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