Create toast when log out (iOS)

Question

I'm working for an app that has users. One of the functionalities is to allow a user to log out and be redirected to the first page. I came across the problem when a user logs out, a toast message "You logged out" should be displayed on the first view of the app and receiving the command from a different page. Basically a toast message that can work with all the views, not only with the current one.

I managed to call a toast function after a user logs out but it won't show the message because the current view is dismissed before to have the chance showing it.

This is the function called:

func showToast(controller: UIViewController, message : String, seconds: Double) {

    let alert = UIAlertController(title: nil, message: message, preferredStyle: .alert)
    alert.view.backgroundColor = UIColor.black
    alert.view.alpha = 0.6
    alert.view.layer.cornerRadius = 15
    controller.present(alert, animated: true)

    DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + seconds) {
        alert.dismiss(animated: true)
    }
}

Answer 1

1. If you dont know which the current presented VC is you could use this extension here:

   extension UIWindow {
   func topViewController() -> UIViewController? {
       var top = self.rootViewController
       while true {
           if let presented = top?.presentedViewController {
               top = presented
           } else if let nav = top as? UINavigationController {
               top = nav.visibleViewController
           } else if let tab = top as? UITabBarController {
               top = tab.selectedViewController
           } else {
               break
           }
       }
       return top
   }
   

   }

Then you can call it it this way:

if let topVC = UIApplication.shared.keyWindow?.topViewController() {
    topVC.present(alert, animated: true)
}

2. Another option is that you pop/dismiss your viewcontroller after you dismissed your alert:

   DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + seconds) {
   alert.dismiss(animated: true)
   // popViewController or dismiss here
   }