在根视图上显示另一个视图时，警报视图中心会更改

Question

In the app, I'm showing an alert when there is no internet connection (Showing on root view controller). There is a Biometric authentication on the application too. So whenever Biometric page appears (Biometric page also shows on root view controller) on the top of the alertview and removes that from the view, alert view constraints changes and doesn't show in the middle.

Step 1:-

Shows Error message

Showing alert Code :-

  func showAlert(title:String, message: String, buttons: [UIAlertAction]) {
    // create the alert
    self.alert.title = title
    self.alert.message = message

    // add an action (button)
    if buttons.count == 0 {
        self.alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
    } else {
        for i in 0...buttons.count-1 {
            self.alert.addAction(buttons[i])
        }
    }
    self.viewController.present(alert, animated: true, completion: nil)
}

Step 2:-

Exit the application and shows the biometric verification view.

App Delegate File :-

   func applicationDidBecomeActive(_ application: UIApplication) {

    if self.userToken != "" && self.biometricStatus && !UserAccessTemp.isBiometricActive {

        let controller = BiometricCheckViewController.instantiate(fromAppStoryboard: .BiometricCheck)
        if let window = self.window, let rootViewController = window.rootViewController {
            var currentController = rootViewController
            while let presentedController = currentController.presentedViewController {
                currentController = presentedController
            }
            currentController.present(controller, animated: true, completion: nil)
        }

    }

Step 3:-

Alert View alignment changes after dismiss the biometric verification view

So how can I re-center the alert view after the Biometric view dismiss?

Answer 1

Just put makeKeyAndVisible() to the Biometric view, and it does fix the problem. Thanks to the Deepika's comment.

func applicationDidBecomeActive(_ application: UIApplication) {

    if self.userToken != "" && self.biometricStatus && !UserAccessTemp.isBiometricActive {

        let controller = BiometricCheckViewController.instantiate(fromAppStoryboard: .BiometricCheck)

        let alertWindow = UIWindow(frame: UIScreen.main.bounds)
        alertWindow.rootViewController = UIViewController()
        alertWindow.windowLevel = UIWindowLevelAlert + 1;
        alertWindow.makeKeyAndVisible()
        alertWindow.rootViewController?.present(controller, animated: true, completion: nil)
    }
}

Answer 2

try:

func showAlert(title:String, message: String, buttons: [UIAlertAction]) {
    // create the alert
    self.alert.title = title
    self.alert.message = message

    // add an action (button)
    if buttons.count == 0 {
        self.alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
    } else {
        for i in 0...buttons.count-1 {
            self.alert.addAction(buttons[i])
        }
    }

    if var topController = UIApplication.sharedApplication().keyWindow?.rootViewController {
        while let presentedViewController = topController.presentedViewController {
            topController = presentedViewController
        }

        topController.present(alert, animated: true, completion: nil)
    }
}