Fix issue with CaptureMethod.Manual on iOS.

[alex-gutev]

This pull request fixes a bug in the stripe_ios package where the intent configuration capture method is ignored, when using deferred payments.

Steps to reproduce the bug

1. Add captureMethod: CaptureMethod.Manual to the IntentMode in the deferred payments example from https://docs.page/flutter-stripe/flutter_stripe/sheet_deferred

   Future<void> initPaymentSheet() async {
       try {
         // 1. create payment intent on the server
         final data = await _createTestPaymentSheet();
   
         // 2. initialize the payment sheet
        await Stripe.instance.initPaymentSheet(
           paymentSheetParameters: SetupPaymentSheetParameters(
             // Enable custom flow
             customFlow: false,
             // Main params
             merchantDisplayName: 'Flutter Stripe Store Demo',
             intentConfiguration: IntentConfiguration(
                 mode: IntentMode(
                   currencyCode: 'USD',
                   amount: 1500,
                   captureMethod: CaptureMethod.Manual
                 ),
                 confirmHandler: (method, saveFuture) {
                   // This is the method where you call the server to create a paymentintent for the payment method id supplied in the callback.
                   _createIntentAndConfirmToUser(method.id);
                 }),         
             // Customer keys
             customerEphemeralKeySecret: data['ephemeralKey'],
             customerId: data['customer'],
             // Extra options
             testEnv: true,
             applePay: true,
             googlePay: true,
             style: ThemeMode.dark,
             merchantCountryCode: 'DE',
           ),
         );
         setState(() {
           _ready = true;
         });
       } catch (e) {
         ScaffoldMessenger.of(context).showSnackBar(
           SnackBar(content: Text('Error: $e')),
         );
         rethrow;
       }
   }

2. Update the backend to create a payment intent with the capture method set to manual.

3. Run the example on iOS.

Expected result:

The payment intent is confirmed when the user taps the pay button in the payment sheet.

Actual result:

The following error is printed in the payment sheet:

"An error occurred in PaymentSheet. Your PaymentIntent captureMethod (manual) does not match the PaymentIntent.IntentConfiguration amount (automatic)"

The captureMethod parameter is ignored by the stripe_ios package and the automatic capture method is always used regardless of the value given for captureMethod.

[jonasbark]

This looks correct to me. However, you'd need to do this pull request to https://github.com/stripe/stripe-react-native because this change would be overwritten (and lost) once we synchronize their sources with ours

[alex-gutev]

I see they have the exact same bug.

[alex-gutev]

I've opened a pull request on the react-native library. stripe/stripe-react-native#1782