title: How to trigger 3DSecure with PaymentIntent on Xamarin.iOs?
body: <p>I've setup payment with Stripe.net on Xamarin iOs.
  I collect Card datas and use a PaymentIntent to confirm the payment.
  (the PaymentIntent is created by the server, I just confirm it).</p>
  
  <p>It's working fine except when I use a 3DSecure card. 
  I'm supposed to get a url to open so that the user can perform the 3DSecure check, but all I get in next_action is a blank url.</p>
  
  <hr>
  
  <p>EDIT : see taintedzodiac answer below :</p>
  
  <p>Adding a return_url parameter to the PaymentIntent changes it to manual authentication mode, which allow us to get the url in the next_action object</p>
  
  <p>It's a good enough answer for now, but it would be better to have a view that automatically trigger the 3DSecure popup if needed, like in iOs.</p>
  
  <hr>
  
  <p>Is there another way to perform the payment that would automatically trigger the 3DSecure popup in xamarin.ios ?</p>
  
  <p>Here is how I create the paymentIntent :</p>
  
  <pre><code>PaymentIntentConfirmOptions optionsConfirm = new PaymentIntentConfirmOptions
                      {
                          PaymentMethodId = _paymentMethod.Id,
                          ClientSecret = intentSecret.client_secret
                      };
  
                      PaymentIntentService paymentIntentService = new PaymentIntentService();
                      PaymentIntent intent = paymentIntentService.Confirm(intentSecret.id, optionsConfirm);
  </code></pre>
  
  <p>The intent returns the following object :</p>
  
  <pre><code>{&lt;Stripe.PaymentIntent@782394758 id=pi_XXXXXXXXXXXXXXXXXX&gt; JSON: {
    "id": "pi_XXXXXXXXXXXXXXXXXX",
    "object": "payment_intent",
    "amount": 5000,
    "amount_capturable": null,
    "amount_received": null,
    "application": null,
    "application_fee_amount": null,
    "canceled_at": null,
    "cancellation_reason": null,
    "capture_method": "automatic",
    "charges": null,
    "client_secret": "pi_XXXXXXXXXXXXXXXXXX",
    "confirmation_method": "automatic",
    "created": 1567605523,
    "currency": "eur",
    "customer": null,
    "description": null,
    "invoice": null,
    "last_payment_error": null,
    "livemode": false,
    "metadata": null,
    "next_action": {
      "redirect_to_url": null,
      "type": "use_stripe_sdk"
    },
    "on_behalf_of": null,
    "payment_method": "pm_XXXXXXXXXXXXXXXXXX",
    "payment_method_options": null,
    "payment_method_types": [
      "card"
    ],
    "receipt_email": null,
    "review": null,
    "setup_future_usage": null,
    "shipping": null,
    "source": null,
    "statement_descriptor": null,
    "statement_descriptor_suffix": null,
    "status": "requires_action",
    "transfer_data": null,
    "transfer_group": null,
    "allowed_source_types": null
  }}
  </code></pre>
  
  <p>Thank you for your help !</p>