Send CBC preferred network in confirm call (#2965)

## Summary
- We now send card[networks][preferred] the network call when confirming
a CBC intent
- When no card brand is selected we omit `networks` from card params
entirley.

## Motivation

https://docs.google.com/document/d/1T12LgVTkEv-LaDtQO3lGgNDt3nV_mwrUOJWgfUmTa9U/edit

## Testing
- New unit tests
- Manual

## Changelog
See diff

CHANGELOG.md

@@ -1,4 +1,7 @@
-## X.X.X
+## x.x.x x-x-x
+### PaymentSheet
+* [Fixed] Fixed an issue when advancing from the country dropdown that prevented user's' from typing in their postal code. ([#2936](https://github.com/stripe/stripe-ios/issues/2936))
+
 ### PaymentsUI
 * [Fixed] An issue with `STPPaymentCardTextField`, where the `paymentCardTextFieldDidChange` delegate method wasn't being called after deleting an empty sub field.
 

Stripe/StripeiOSTests/STPCardBrandTest.swift

@@ -49,4 +49,45 @@ class STPCardBrandTest: XCTestCase {
             }
         }
     }
+
+    func testApiValueFromBrand() {
+        let brands = [
+            STPCardBrand.visa,
+            STPCardBrand.amex,
+            STPCardBrand.mastercard,
+            STPCardBrand.discover,
+            STPCardBrand.JCB,
+            STPCardBrand.dinersClub,
+            STPCardBrand.unionPay,
+            STPCardBrand.cartesBancaires,
+            STPCardBrand.unknown,
+        ]
+
+        for brand in brands {
+            let string = STPCardBrandUtilities.apiValue(from: brand)
+
+            switch brand {
+            case .amex:
+                XCTAssertEqual(string, "american_express")
+            case .dinersClub:
+                XCTAssertEqual(string, "diners_club")
+            case .discover:
+                XCTAssertEqual(string, "discover")
+            case .JCB:
+                XCTAssertEqual(string, "jcb")
+            case .mastercard:
+                XCTAssertEqual(string, "mastercard")
+            case .unionPay:
+                XCTAssertEqual(string, "unionpay")
+            case .visa:
+                XCTAssertEqual(string, "visa")
+            case .cartesBancaires:
+                XCTAssertEqual(string, "cartes_bancaires")
+            case .unknown:
+                XCTAssertEqual(string, "unknown")
+            @unknown default:
+                break
+            }
+        }
+    }
 }

Stripe/StripeiOSTests/STPPaymentMethodCardParamsTest.swift

@@ -19,11 +19,13 @@ class STPPaymentMethodCardParamsTest: XCTestCase {
         params1.cvc = "123"
         params1.expYear = 22
         params1.expMonth = 12
+        params1.networks = .init(preferred: "visa")
         let params2 = STPPaymentMethodCardParams()
         params2.number = "4242424242424242"
         params2.cvc = "123"
         params2.expYear = 22
         params2.expMonth = 12
+        params2.networks = .init(preferred: "visa")
         XCTAssertEqual(params1, params2)
         params1.additionalAPIParameters["test"] = "bla"
         XCTAssertNotEqual(params1, params2)
@@ -65,4 +67,33 @@ class STPPaymentMethodCardParamsTest: XCTestCase {
         XCTAssertEqual(cardParams.addressCountry, "US")
         XCTAssertEqual(cardParams.addressZip, "12345")
     }
+
+    func testPropertyNamesToFormFieldsMapping() {
+        // Test for STPPaymentMethodCardParams
+        let cardParams = STPPaymentMethodCardParams()
+
+        let cardParamsExpectedMapping = [
+            "number": "number",
+            "expMonth": "exp_month",
+            "expYear": "exp_year",
+            "cvc": "cvc",
+            "token": "token",
+            "networks": "networks",
+        ]
+
+        let cardParamsMapping = type(of: cardParams).propertyNamesToFormFieldNamesMapping()
+
+        XCTAssertEqual(cardParamsMapping, cardParamsExpectedMapping)
+
+        // Test for STPPaymentMethodCardNetworksParams
+        let networksParams = STPPaymentMethodCardNetworksParams()
+
+        let networksParamsExpectedMapping = [
+            "preferred": "preferred",
+        ]
+
+        let networksParamsMapping = type(of: networksParams).propertyNamesToFormFieldNamesMapping()
+
+        XCTAssertEqual(networksParamsMapping, networksParamsExpectedMapping)
+    }
 }

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/Elements/CardSectionWithScanner/CardSectionWithScannerElement.swift

@@ -72,12 +72,20 @@ final class CardSection: ContainerElement {
                 return params
             }
             : nil
-        var cardBrandDropDown: DropdownFieldElement?
+        var cardBrandDropDown: PaymentMethodElementWrapper<DropdownFieldElement>?
         if cardBrandChoiceEligible {
-            cardBrandDropDown = DropdownFieldElement.makeCardBrandDropdown(theme: theme)
+            cardBrandDropDown = PaymentMethodElementWrapper(DropdownFieldElement.makeCardBrandDropdown(theme: theme)) { field, params in
+                guard let cardBrandCaseIndex = Int(field.selectedItem.rawData),
+                      let cardBrand: STPCardBrand = .init(rawValue: cardBrandCaseIndex) else {
+                    return params
+                }
+
+                cardParams(for: params).networks = STPPaymentMethodCardNetworksParams(preferred: STPCardBrandUtilities.apiValue(from: cardBrand))
+                return params
+            }
         }
         let panElement = PaymentMethodElementWrapper(TextFieldElement.PANConfiguration(defaultValue: defaultValues.pan,
-                                                                                       cardBrandDropDown: cardBrandDropDown), theme: theme) { field, params in
+                                                                                       cardBrandDropDown: cardBrandDropDown?.element), theme: theme) { field, params in
             cardParams(for: params).number = field.text
             return params
         }
@@ -108,7 +116,7 @@ final class CardSection: ContainerElement {
 
         let allSubElements: [Element?] = [
             nameElement,
-            panElement,
+            panElement, SectionElement.HiddenElement(cardBrandDropDown),
             SectionElement.MultiElementRow([expiryElement, cvcElement], theme: theme),
         ]
         let subElements = allSubElements.compactMap { $0 }
@@ -120,7 +128,7 @@ final class CardSection: ContainerElement {
 
         self.nameElement = nameElement?.element
         self.panElement = panElement.element
-        self.cardBrandDropDown = cardBrandDropDown
+        self.cardBrandDropDown = cardBrandDropDown?.element
         self.cvcElement = cvcElement.element
         self.expiryElement = expiryElement.element
         cardSection.delegate = self

StripePayments/StripePayments/Source/API Bindings/Models/PaymentMethods/Types/STPPaymentMethodCardNetworksParams.swift

@@ -0,0 +1,50 @@
+//
+//  STPPaymentMethodCardNetworksParams.swift
+//  StripePayments
+//
+//  Created by Nick Porter on 9/28/23.
+//
+
+import Foundation
+
+public class STPPaymentMethodCardNetworksParams: NSObject, STPFormEncodable {
+
+    @objc public var additionalAPIParameters: [AnyHashable: Any] = [:]
+
+    /// The network that your user selected for this payment
+    /// method. This must reflect an explicit user choice. If your user didn't
+    /// make a selection, then pass `null`.
+    @objc public var preferred: String?
+
+    @objc public convenience init(preferred: String?) {
+        self.init()
+        self.preferred = preferred
+    }
+
+    // MARK: - Description
+    /// :nodoc:
+    @objc public override var description: String {
+        let props = [
+            // Object
+            String(format: "%@: %p", NSStringFromClass(STPPaymentMethodCardNetworksParams.self), self),
+            // Preferred
+            "preferred = \(preferred ?? "")",
+        ]
+
+        return "<\(props.joined(separator: "; "))>"
+    }
+
+    // MARK: - STPFormEncodable
+
+    @objc
+    public class func rootObjectName() -> String? {
+        return "networks"
+    }
+
+    @objc
+    public static func propertyNamesToFormFieldNamesMapping() -> [String: String] {
+        return [
+            NSStringFromSelector(#selector(getter: preferred)): "preferred",
+        ]
+    }
+}

StripePayments/StripePayments/Source/API Bindings/Models/PaymentMethods/Types/STPPaymentMethodCardParams.swift

@@ -39,8 +39,10 @@ public class STPPaymentMethodCardParams: NSObject, STPFormEncodable {
     @objc public var token: String?
     /// Card security code. It is highly recommended to always include this value.
     @objc public var cvc: String?
-    /// The last 4 digits of the card.
+    /// Information about the networks to use with this payment method.
+    @objc public var networks: STPPaymentMethodCardNetworksParams?
 
+    /// The last 4 digits of the card.
     @objc public var last4: String? {
         if number != nil && (number?.count ?? 0) >= 4 {
             return (number as NSString?)?.substring(from: (number?.count ?? 0) - 4) ?? ""
@@ -60,6 +62,7 @@ public class STPPaymentMethodCardParams: NSObject, STPFormEncodable {
             "expMonth = \(expMonth ?? 0)",
             "expYear = \(expYear ?? 0)",
             "cvc = \(((cvc) != nil ? "<redacted>" : nil) ?? "")",
+            "networks = \(networks?.description ?? "")",
             // Token
             "token = \(token ?? "")",
         ]
@@ -82,6 +85,7 @@ public class STPPaymentMethodCardParams: NSObject, STPFormEncodable {
             NSStringFromSelector(#selector(getter: expYear)): "exp_year",
             NSStringFromSelector(#selector(getter: cvc)): "cvc",
             NSStringFromSelector(#selector(getter: token)): "token",
+            NSStringFromSelector(#selector(getter: networks)): "networks",
         ]
     }
 
@@ -93,6 +97,7 @@ public class STPPaymentMethodCardParams: NSObject, STPFormEncodable {
         copyCardParams.expMonth = expMonth
         copyCardParams.expYear = expYear
         copyCardParams.cvc = cvc
+        copyCardParams.networks = networks
         return copyCardParams
     }
 
@@ -119,6 +124,6 @@ public class STPPaymentMethodCardParams: NSObject, STPFormEncodable {
         }
 
         return number == other?.number && expMonth == other?.expMonth && expYear == other?.expYear
-            && cvc == other?.cvc && token == other?.token
+            && cvc == other?.cvc && token == other?.token && networks?.preferred == other?.networks?.preferred
     }
 }

StripePayments/StripePayments/Source/API Bindings/Models/STPCardBrand.swift

@@ -73,4 +73,31 @@ public class STPCardBrandUtilities: NSObject {
         }
     }
 
+    /// Returns brand API string value from given card brand.
+    ///
+    /// - Parameter brand: The `STPCardBrand` to transform into a string.
+    /// - Returns: A `String` representing the card brand. This could be "visa",
+    @objc(apiValueFromCardBrand:) public static func apiValue(from brand: STPCardBrand) -> String {
+        switch brand {
+        case .visa:
+            return "visa"
+        case .amex:
+            return "american_express"
+        case .mastercard:
+            return "mastercard"
+        case .discover:
+            return "discover"
+        case .JCB:
+            return "jcb"
+        case .dinersClub:
+            return "diners_club"
+        case .unionPay:
+            return "unionpay"
+        case .cartesBancaires:
+            return "cartes_bancaires"
+        default:
+            return "unknown"
+        }
+    }
+
 }

StripeUICore/StripeUICore/Source/Elements/DropdownFieldElement.swift

@@ -254,7 +254,10 @@ extension DropdownFieldElement: PickerFieldViewDelegate {
             didUpdate?(selectedIndex)
         }
         previouslySelectedIndex = selectedIndex
-        delegate?.continueToNextField(element: self)
+        DispatchQueue.main.async { [weak self] in
+            guard let self = self else { return }
+            self.delegate?.continueToNextField(element: self)
+        }
     }
 
     func didCancel(_ pickerFieldView: PickerFieldView) {

StripeUICore/StripeUICore/Source/Elements/Section/SectionElement.swift

@@ -31,7 +31,7 @@ import UIKit
     }
     var viewModel: SectionViewModel {
         return ViewModel(
-            views: elements.map({ $0.view }),
+            views: elements.filter { !($0.view is HiddenElement.HiddenView) }.map({ $0.view }), // filter out hidden views to prevent showing the separator
             title: title,
             errorText: errorText,
             subLabel: subLabel,
@@ -102,3 +102,28 @@ extension SectionElement: ElementDelegate {
         delegate?.didUpdate(element: self)
     }
 }
+
+// MARK: HiddenElement
+
+extension SectionElement {
+    /// A simple container element where the element's view is hidden
+    /// Useful when an element is a part of a section but it's view is embeded into another element
+    /// E.g. card brand drop down embedded into the PAN textfield
+    @_spi(STP) public final class HiddenElement: ContainerElement {
+        final class HiddenView: UIView {}
+
+        weak public var delegate: ElementDelegate?
+        public lazy var view: UIView = {
+            return HiddenView(frame: .zero) // Hide the element's view
+        }()
+        public let elements: [Element]
+
+        public init?(_ element: Element?) {
+            guard let element = element else {
+                return nil
+            }
+            self.elements = [element]
+            element.delegate = self
+        }
+    }
+}