After reading this question: How to set back button text in Swift,
I started moving the code I was using to configure the nav bar right button to the view controller that calls the xib I'm presenting (ParticipantEditorViewController) like so:
import UIKit
class ViewController: UIViewController {
    /*
     * This is placeholder class. The code below will need to be added to whichever view controllers summon the participant editor, in their prepareForSegue method.
     */
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        print("snap")
        if let participantEditor = segue.destinationViewController as? ParticipantEditorViewController {
            print("crackle")
            let barButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Action, target: participantEditor, action: nil)
//            let barButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Action, target: participantEditor, action: Selector(participantEditor.presentActionMenu()))
            print("pop")
            navigationItem.rightBarButtonItem = barButton
        }
    }
}
But I'm still not able to configure the nav bar programmatically. Any help on what I'm missing?
 
     
    