Segue

1. ViewController
 // In a storyboard-based application, you will often want to do a little preparation before navigation
  override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    
  // hier fehlt Code    
}


2/3./4. ViewController, für alle
  @IBAction override func unwind(for unwindSegue: UIStoryboardSegue, towards subsequentVC: UIViewController) {
             //  hier fehlt kein Quellcode
     }