title: ApplePay PKPaymentAuthorizationViewController always shows processing
body: <p><img src="https://i.stack.imgur.com/z5Bed.jpg" alt="enter image description here"> I am trying to use Apple Pay in my app. It works fine to present PKPaymentAuthorizationViewController. However, after I filled up with credit card and billing information, it just shows a spinning wheel and 'processing' as shown in the picture.</p>
  
  <p>The code for presenting Apple Pay view controller is as follows:</p>
  
  <pre><code>let request = Stripe.paymentRequestWithMerchantIdentifier(DH_APPLEPAY_ID)
  request.paymentSummaryItems = [PKPaymentSummaryItem(label: label, amount: amountDecimal)]
  
  request.requiredBillingAddressFields = PKAddressField.All
  request.requiredShippingAddressFields = PKAddressField.PostalAddress | PKAddressField.Email
  request.countryCode = "US"
  request.currencyCode = "USD"
  request.merchantCapabilities = PKMerchantCapability.CapabilityEMV | PKMerchantCapability.Capability3DS
  request.supportedNetworks = [PKPaymentNetworkAmex, PKPaymentNetworkMasterCard, PKPaymentNetworkVisa]
  
  if Stripe.canSubmitPaymentRequest(request) {
  
      let paymentController = PKPaymentAuthorizationViewController(paymentRequest: request)
  
      paymentController.delegate = self
  
      self.navigationController?.presentViewController(paymentController, animated: true, completion: nil)
  } else {
      //popup
      DHUtils.alert("Apple Pay", message: "Please add your credit card to Passbook.", inViewController: self)
  }
  </code></pre>
  
  <p>The <code>func paymentAuthorizationViewController(controller: PKPaymentAuthorizationViewController!, didAuthorizePayment payment: PKPayment!, completion: ((PKPaymentAuthorizationStatus) -&gt; Void)!)</code> delegate never get called.</p>
  
  <p>The certificate status looks all right. What do I miss here to make it work?</p>