Listening or Results

You can leverage MetricSDKs internal notification manager or use your own notification handler. Add a NotificationCenter observer to the viewDidLoad() of the view controller that launched your SDK. And pass in your @objc marked function as the selector. Eg. In this case we use handleVerificationOutcome(). You can call deinit but that's not really necessary if you're using Swift 4.2+.

...
import MetricSDK
...
class ViewController: UIViewController {
   ...
   override func viewDidLoad(){
       super.viewDidLoad()
       ...
       MetricNotificationManager.shared.addObserver(observer: self,
                                                    selector: #selector(handleVerificationOutcome),
                                                    name: NotificationKeys.VERIFICATION_COMPLETE)
   }
   ...
   
   @objc func handleVerificationOutcome(_ notification: Notification) {
   if let outcome = notification.object as? VerificationOutcome {
       switch outcome {
       case .success:
           //update your UI, etc..
           print("Verification successful")
       case .failed(let reason):
           //update your UI, etc..
           print("Session Failed: \(reason)")
       default:
           break
           }
       }
   }
}

In modern Swift, specifically from Swift 4.2 onwards, you generally do not need to manually remove observers for notifications, as they are automatically deregistered when the object is deallocated.

deinit{
     NotificationCenter.default.removeObserver(self, name: NotificationKeys.VERIFICATION_COMPLETE, object: nil)
}