如何在Skscene中呈现UIAlert

Question

When presenting a UIAlert in SKScene nothing shows up Here is the code

 var alertController = UIAlertController(title: "Nothing Selected",
                                            message: "You have selected a picture.",
                                            preferredStyle: UIAlertControllerStyle.alert)
    alertController.addAction(UIAlertAction(title: "HI!", style: UIAlertActionStyle.cancel, handler: nil))
    self.view?.window?.rootViewController?.present(alertController, animated: true, completion: nil)

Answer 1

From within the scene you need to present the Alert Controller at the root View Controller level.

if let vc = self.scene?.view?.window?.rootViewController {
    vc.present(alertController, animated: true, completion: nil)
}

Answer 2

Try to present from the top view controller returned by this extension (taken from this post ):

extension UIApplication {

    class func topViewController(controller: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
        if let navigationController = controller as? UINavigationController {
            return topViewController(controller: navigationController.visibleViewController)
        }
        if let tabController = controller as? UITabBarController {
            if let selected = tabController.selectedViewController {
                return topViewController(controller: selected)
            }
        }
        if let presented = controller?.presentedViewController {
            return topViewController(controller: presented)
        }
        return controller
    }

}