Perform segue after notification access has been granted

I would like to know how to perform a modal segue after the remote notification access has been granted from the dialog box. I have set up my remote notification in the app delegate.

func registerANSForApplication(_ application: UIApplication,withBlock block: @escaping (_ granted:Bool) -> (Void)){
    InstanceID.instanceID().instanceID { (result, error) in
        if let error = error {
            print("Error fetching remote instange ID: \(error)")
        } else if let result = result {
            print("Remote instance ID token: \(result.token)")
            AppDelegate.isToken = result.token
        }
    }
    let current  = UNUserNotificationCenter.current()
    let options : UNAuthorizationOptions = [.sound, .badge, .alert]

    current.requestAuthorization(options: options) { (granted, error) in
        guard granted else{
            return
        }
        if error != nil{
            print(error?.localizedDescription ?? "")
        }else{
            Messaging.messaging().delegate = self
            current.delegate = self
            DispatchQueue.main.async {
                application.registerForRemoteNotifications()
            }
        }
    }

}

Then, in my view controller, I have this code:

let appDelegate = UIApplication.shared.delegate as! 
appDelegate.registerANSForApplication(UIApplication.shared) { (granted) -> (Void) in
    self.performSegue(withIdentifier: "MembershipVC", sender: nil)
}

The problem is whether the user allows or denies the access to notification, the segue is not executed.

Thank you for your help.

You have to call the block parameter

Replace

current.requestAuthorization(options: options) { (granted, error) in
    guard granted else{
        return
    }
    if error != nil{
        print(error?.localizedDescription ?? "")
    }else{
        Messaging.messaging().delegate = self
        current.delegate = self
        DispatchQueue.main.async {
            application.registerForRemoteNotifications()
        }
    }
}

with

current.requestAuthorization(options: options) { (granted, error) in
    if error != nil {
        print(error?.localizedDescription ?? "")
        block(false)
    } else {
        Messaging.messaging().delegate = self
        current.delegate = self
        DispatchQueue.main.async {
            application.registerForRemoteNotifications()
            block(granted)
        }
    }

}