How to present UIAlertController when not in a view controller?

Question

Scenario: The user taps on a button on a view controller. The view controller is the topmost (obviously) in the navigation stack. The tap invokes a utility class method call

Answer 1

Cross post my answer since these two threads are not flagged as dupes...

Now that UIViewController is part of the responder chain, you can do something like this:

if let vc = self.nextResponder()?.targetForAction(#selector(UIViewController.presentViewController(_:animated:completion:)), withSender: self) as? UIViewController {

    let alert = UIAlertController(title: "A snappy title", message: "Something bad happened", preferredStyle: .Alert)
    alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))

    vc.presentViewController(alert, animated: true, completion: nil)
}