title: Change UIAlertController message or title during its presentation
body: <p>Is posible change the title or message text of <code>UIAlertController</code> while its <code>ViewController</code> is presenting.</p>
  
  <p>For example I present an alert when a user press a button with this message: </p>
  
  <p>"Waiting for redeem code"</p>
  
  <p>Then I use <strong>Alamofire</strong> to make a request and get the code, after I have it I want to change the message from alert without dissmising and presenting it again, for example the new message text is it: </p>
  
  <p>"Your redeem code is : ########"</p>
  
  <p><strong>Updated</strong></p>
  
  <p>Here is my code: </p>
  
  <pre><code>@IBAction func offerAction(_ sender: UIButton) {
          var code: String = "Generating códe"
          let message: String = "El código para redimir esta oferta es: \(code)"
  
          let alert = UIAlertController(title: nil, message: message, preferredStyle: .alert)
          let okAction = UIAlertAction(title: "Accept", style: .default, handler: nil)
          let redirect = UIAlertAction(title: "Website", style: .default) { (_) in
              // TODO open url web
          }
  
          if offer.redeemOfferOnline == .yes {
              alert.addAction(redirect)
          }
          alert.addAction(okAction)
          present(alert, animated: true, completion: nil)
  
          offer.code.getRedeemCode(id: offer.id) { (success, data) in
              if success {
                  code = data
                  alert.message = message
  
                  // TODO end the code of changing the message of alert
              }
          }
  }
  </code></pre>