Read the default_payment_method field from elements session and use t…

…hat as the default PM (#4313)

## Summary
<!-- Simple summary of what was changed. -->
Added allowsSetAsDefaultPM flag. Only shown if we're using customer
session.
If allowsSetAsDefaultPM is on, then instead of reading from the locally
stored default, we read from ElementsSession.
## Motivation
<!-- Why are you making this change? If it's for fixing a bug, if
possible, please include a code snippet or example project that
demonstrates the issue. -->
[MOBILESDK-2799](https://jira.corp.stripe.com/browse/MOBILESDK-2799)
## Testing
<!-- How was the code tested? Be as specific as possible. -->
customer_session, allowsSetAsDefaultPM on
Hardcoded the value that was "read" from default_payment_method (set to
the 4242 Visa stripe id)
After changing the selected payment method and paying with it, upon
reload the PaymentSheet default is back to our hardcoded default.



https://github.com/user-attachments/assets/38601a0e-513b-40a8-a3d8-f30069723f97



## Changelog


<!-- Is this a notable change that affects users? If so, add a line to
`CHANGELOG.md` and prefix the line with one of the following:
    - [Added] for new features.
    - [Changed] for changes in existing functionality.
    - [Deprecated] for soon-to-be removed features.
    - [Removed] for now removed features.
    - [Fixed] for any bug fixes.
    - [Security] in case of vulnerabilities.
-->

Example/PaymentSheet Example/PaymentSheet Example/CustomerSheetTestPlayground.swift

@@ -53,6 +53,7 @@ struct CustomerSheetTestPlayground: View {
                                 SettingPickerView(setting: $playgroundController.settings.paymentMethodRemove)
                                 SettingPickerView(setting: $playgroundController.settings.paymentMethodRemoveLast)
                                 SettingPickerView(setting: $playgroundController.settings.paymentMethodAllowRedisplayFilters)
+                                SettingPickerView(setting: $playgroundController.settings.allowsSetAsDefaultPM)
                             }
                         }
                     }

Example/PaymentSheet Example/PaymentSheet Example/CustomerSheetTestPlaygroundController.swift

@@ -4,7 +4,7 @@
 //
 
 import Combine
-@_spi(STP) @_spi(CustomerSessionBetaAccess) @_spi(CardBrandFilteringBeta) import StripePaymentSheet
+@_spi(STP) @_spi(CustomerSessionBetaAccess) @_spi(CardBrandFilteringBeta) @_spi(AllowsSetAsDefaultPM) import StripePaymentSheet
 import SwiftUI
 
 class CustomerSheetTestPlaygroundController: ObservableObject {
@@ -147,6 +147,7 @@ class CustomerSheetTestPlaygroundController: ObservableObject {
         case .allowVisa:
             configuration.cardBrandAcceptance = .allowed(brands: [.visa])
         }
+        configuration.allowsSetAsDefaultPM = settings.allowsSetAsDefaultPM == .on
         return configuration
     }
 

Example/PaymentSheet Example/PaymentSheet Example/CustomerSheetTestPlaygroundSettings.swift

@@ -148,6 +148,12 @@ public struct CustomerSheetTestPlaygroundSettings: Codable, Equatable {
         case allowVisa
     }
 
+    enum AllowsSetAsDefaultPM: String, PickerEnum {
+        static let enumName: String = "allowsSetAsDefaultPM"
+        case on
+        case off
+    }
+
     var customerMode: CustomerMode
     var customerId: String?
     var customerKeyType: CustomerKeyType
@@ -169,6 +175,7 @@ public struct CustomerSheetTestPlaygroundSettings: Codable, Equatable {
     var paymentMethodRemoveLast: PaymentMethodRemoveLast
     var paymentMethodAllowRedisplayFilters: PaymentMethodAllowRedisplayFilters
     var cardBrandAcceptance: CardBrandAcceptance
+    var allowsSetAsDefaultPM: AllowsSetAsDefaultPM
 
     static func defaultValues() -> CustomerSheetTestPlaygroundSettings {
         return CustomerSheetTestPlaygroundSettings(customerMode: .new,
@@ -190,7 +197,8 @@ public struct CustomerSheetTestPlaygroundSettings: Codable, Equatable {
                                                    paymentMethodRemove: .enabled,
                                                    paymentMethodRemoveLast: .enabled,
                                                    paymentMethodAllowRedisplayFilters: .always,
-                                                   cardBrandAcceptance: .all)
+                                                   cardBrandAcceptance: .all,
+                                                   allowsSetAsDefaultPM: .off)
     }
 
     var base64Data: String {

Example/PaymentSheet Example/PaymentSheet Example/PaymentSheetTestPlayground.swift

@@ -119,6 +119,7 @@ struct PaymentSheetTestPlayground: View {
                                 if playgroundController.settings.paymentMethodRedisplay == .enabled {
                                     SettingPickerView(setting: $playgroundController.settings.paymentMethodAllowRedisplayFilters)
                                 }
+                                SettingPickerView(setting: $playgroundController.settings.allowsSetAsDefaultPM)
                             }
                         }
                     }

Example/PaymentSheet Example/PaymentSheet Example/PaymentSheetTestPlaygroundSettings.swift

@@ -444,6 +444,12 @@ struct PaymentSheetTestPlaygroundSettings: Codable, Equatable {
         case allowVisa
     }
 
+    enum AllowsSetAsDefaultPM: String, PickerEnum {
+        static let enumName: String = "allowsSetAsDefaultPM"
+        case on
+        case off
+    }
+
     var uiStyle: UIStyle
     var layout: Layout
     var mode: Mode
@@ -490,6 +496,7 @@ struct PaymentSheetTestPlaygroundSettings: Codable, Equatable {
     var formSheetAction: FormSheetAction
     var embeddedViewDisplaysMandateText: DisplaysMandateTextEnabled
     var cardBrandAcceptance: CardBrandAcceptance
+    var allowsSetAsDefaultPM: AllowsSetAsDefaultPM
 
     static func defaultValues() -> PaymentSheetTestPlaygroundSettings {
         return PaymentSheetTestPlaygroundSettings(
@@ -535,7 +542,8 @@ struct PaymentSheetTestPlaygroundSettings: Codable, Equatable {
             collectAddress: .automatic,
             formSheetAction: .confirm,
             embeddedViewDisplaysMandateText: .on,
-            cardBrandAcceptance: .all)
+            cardBrandAcceptance: .all,
+            allowsSetAsDefaultPM: .off)
     }
 
     static let nsUserDefaultsKey = "PaymentSheetTestPlaygroundSettings"

Example/PaymentSheet Example/PaymentSheet Example/PlaygroundController.swift

@@ -14,7 +14,7 @@ import Contacts
 import PassKit
 @_spi(STP) import StripeCore
 @_spi(STP) import StripePayments
-@_spi(CustomerSessionBetaAccess) @_spi(STP) @_spi(PaymentSheetSkipConfirmation) @_spi(ExperimentalAllowsRemovalOfLastSavedPaymentMethodAPI) @_spi(EmbeddedPaymentElementPrivateBeta) @_spi(CardBrandFilteringBeta) import StripePaymentSheet
+@_spi(CustomerSessionBetaAccess) @_spi(STP) @_spi(PaymentSheetSkipConfirmation) @_spi(ExperimentalAllowsRemovalOfLastSavedPaymentMethodAPI) @_spi(EmbeddedPaymentElementPrivateBeta) @_spi(CardBrandFilteringBeta) @_spi(AllowsSetAsDefaultPM) import StripePaymentSheet
 import SwiftUI
 import UIKit
 
@@ -184,6 +184,7 @@ class PlaygroundController: ObservableObject {
         case .allowVisa:
             configuration.cardBrandAcceptance = .allowed(brands: [.visa])
         }
+        configuration.allowsSetAsDefaultPM = settings.allowsSetAsDefaultPM == .on
         return configuration
     }
 
@@ -271,6 +272,7 @@ class PlaygroundController: ObservableObject {
         case .allowVisa:
             configuration.cardBrandAcceptance = .allowed(brands: [.visa])
         }
+        configuration.allowsSetAsDefaultPM = settings.allowsSetAsDefaultPM == .on
         return configuration
     }
 

StripePaymentSheet/StripePaymentSheet/Source/Internal/API Bindings/v1-elements-sessions/ElementsCustomer.swift

@@ -39,4 +39,14 @@ struct ElementsCustomer: Equatable, Hashable {
         let defaultPaymentMethod = response["default_payment_method"] as? String
         return ElementsCustomer(paymentMethods: paymentMethods, defaultPaymentMethod: defaultPaymentMethod, customerSession: customerSession)
     }
+
+    func getDefaultOrFirstPaymentMethod() -> STPPaymentMethod? {
+        // if customer has a default payment method from the elements session, return the default payment method
+        let defaultSavedPaymentMethod = paymentMethods.first { $0.stripeId == defaultPaymentMethod }
+        if let defaultSavedPaymentMethod = defaultSavedPaymentMethod {
+            return defaultSavedPaymentMethod
+        }
+        // otherwise, return the first payment method from the customer's list of saved payment methods
+        return paymentMethods.first
+    }
 }

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/CustomerSessionAdapter/CustomerSessionAdapter.swift

@@ -107,7 +107,14 @@ extension CustomerSessionAdapter {
         return stripePaymentMethodId
     }
 
-    func fetchSelectedPaymentOption(for customerId: String) -> CustomerPaymentOption? {
+    func fetchSelectedPaymentOption(for customerId: String, customer: ElementsCustomer? = nil) -> CustomerPaymentOption? {
+        // if opted in to the "set as default" feature, try to get default payment method from elements session
+        if configuration.allowsSetAsDefaultPM {
+            guard let customer = customer,
+                 let defaultPaymentMethod = customer.getDefaultOrFirstPaymentMethod() else { return nil }
+            return CustomerPaymentOption.stripeId(defaultPaymentMethod.stripeId)
+        }
+
         return CustomerPaymentOption.defaultPaymentMethod(for: customerId)
     }
 

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/CustomerSheet/CustomerSheet.swift

@@ -326,7 +326,18 @@ extension CustomerSheet {
         switch customerSheetDataSource.dataSource {
         case .customerSession(let customerSessionAdapter):
             let (elementsSession, customerSessionClientSecret) = try await customerSessionAdapter.elementsSessionWithCustomerSessionClientSecret()
-            let selectedPaymentOption = CustomerPaymentOption.defaultPaymentMethod(for: customerSessionClientSecret.customerId)
+
+            var selectedPaymentOption: CustomerPaymentOption?
+
+            // if opted in to the "set as default" feature, try to get default payment method from elements session
+            if configuration.allowsSetAsDefaultPM {
+                guard let customer = elementsSession.customer,
+                    let defaultPaymentMethod = customer.getDefaultOrFirstPaymentMethod() else { return nil }
+                selectedPaymentOption = CustomerPaymentOption.stripeId(defaultPaymentMethod.stripeId)
+            }
+            else {
+                selectedPaymentOption = CustomerPaymentOption.defaultPaymentMethod(for: customerSessionClientSecret.customerId)
+            }
 
             switch selectedPaymentOption {
             case .applePay:

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/CustomerSheet/CustomerSheetConfiguration.swift

@@ -81,6 +81,11 @@ extension CustomerSheet {
         /// Note: Card brand filtering is not currently supported by Link.
         @_spi(CardBrandFilteringBeta) public var cardBrandAcceptance: PaymentSheet.CardBrandAcceptance = .all
 
+        /// This is an experimental feature that may be removed at any time.
+        /// If true, users can set a payment method as default and sync their default payment method across web and mobile
+        /// If false (default), users cannot set default payment methods.
+        @_spi(AllowsSetAsDefaultPM) public var allowsSetAsDefaultPM = false
+
         public init () {
         }
     }

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/CustomerSheet/CustomerSheetDataSource.swift

@@ -41,8 +41,8 @@ class CustomerSheetDataSource {
                 // Ensure local specs are loaded prior to the ones from elementSession
                 await loadFormSpecs()
                 let customerId = try await customerSessionClientSecret.customerId
-                let paymentOption = customerSessionAdapter.fetchSelectedPaymentOption(for: customerId)
                 let elementSession = try await elementsSessionResult
+                let paymentOption = customerSessionAdapter.fetchSelectedPaymentOption(for: customerId, customer: elementSession.customer)
 
                 // Override with specs from elementSession
                 _ = FormSpecProvider.shared.loadFrom(elementSession.paymentMethodSpecs as Any)

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/Embedded/EmbeddedPaymentElement+Internal.swift

@@ -54,7 +54,16 @@ extension EmbeddedPaymentElement {
             }
 
             // If there's no previous customer input, default to the customer's default or the first saved payment method, if any
-            let customerDefault = CustomerPaymentOption.defaultPaymentMethod(for: configuration.customer?.id)
+            var customerDefault: CustomerPaymentOption?
+            // if opted in to the "set as default" feature, try to get default payment method from elements session
+            if configuration.allowsSetAsDefaultPM {
+                if let defaultPaymentMethod = loadResult.elementsSession.customer?.getDefaultOrFirstPaymentMethod() {
+                    customerDefault = CustomerPaymentOption.stripeId(defaultPaymentMethod.stripeId)
+                }
+            }
+            else {
+                customerDefault = CustomerPaymentOption.defaultPaymentMethod(for: configuration.customer?.id)
+            }
             switch customerDefault {
             case .applePay:
                 return .applePay

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/Embedded/EmbeddedPaymentElementConfiguration.swift

@@ -131,6 +131,11 @@ extension EmbeddedPaymentElement {
         /// Note: Card brand filtering is not currently supported by Link.
         @_spi(CardBrandFilteringBeta) public var cardBrandAcceptance: PaymentSheet.CardBrandAcceptance = .all
 
+        /// This is an experimental feature that may be removed at any time.
+        /// If true, users can set a payment method as default and sync their default payment method across web and mobile
+        /// If false (default), users cannot set default payment methods.
+        @_spi(AllowsSetAsDefaultPM) public var allowsSetAsDefaultPM = false
+
         /// The view can display payment methods like “Card” that, when tapped, open a form sheet where customers enter their payment method details. The sheet has a button at the bottom. `FormSheetAction` enumerates the actions the button can perform.
         public enum FormSheetAction {
             /// The button says “Pay” or “Setup”. When tapped, we confirm the payment or setup in the form sheet.

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/PaymentElementConfiguration.swift

@@ -37,6 +37,7 @@ protocol PaymentElementConfiguration: PaymentMethodRequirementProvider {
     var cardBrandAcceptance: PaymentSheet.CardBrandAcceptance { get set }
     var analyticPayload: [String: Any] { get }
     var disableWalletPaymentMethodFiltering: Bool { get set }
+    var allowsSetAsDefaultPM: Bool { get set }
     var linkPaymentMethodsOnly: Bool { get set }
     var forceNativeLinkEnabled: Bool { get set }
 }

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/PaymentSheetConfiguration.swift

@@ -211,6 +211,10 @@ extension PaymentSheet {
         /// Note: Card brand filtering is not currently supported by Link.
         @_spi(CardBrandFilteringBeta) public var cardBrandAcceptance: PaymentSheet.CardBrandAcceptance = .all
 
+        /// This is an experimental feature that may be removed at any time.
+        /// If true, users can set a payment method as default and sync their default payment method across web and mobile
+        /// If false (default), users cannot set default payment methods.
+        @_spi(AllowsSetAsDefaultPM) public var allowsSetAsDefaultPM = false
     }
 
     /// Defines the layout orientations available for displaying payment methods in PaymentSheet.

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/PaymentSheetLoader.swift

@@ -116,7 +116,9 @@ final class PaymentSheetLoader {
                     savedPaymentMethods: filteredSavedPaymentMethods,
                     customerID: configuration.customer?.id,
                     showApplePay: integrationShape.canDefaultToLinkOrApplePay ? isApplePayEnabled : false,
-                    showLink: integrationShape.canDefaultToLinkOrApplePay ? isLinkEnabled : false
+                    showLink: integrationShape.canDefaultToLinkOrApplePay ? isLinkEnabled : false,
+                    allowsSetAsDefaultPM: configuration.allowsSetAsDefaultPM,
+                    customer: elementsSession.customer
                 )
                 let paymentMethodTypes = PaymentSheet.PaymentMethodType.filteredPaymentMethodTypes(from: intent, elementsSession: elementsSession, configuration: configuration, logAvailability: true)
 
@@ -316,9 +318,18 @@ final class PaymentSheetLoader {
 
         // Move default PM to front
         if let customerID = configuration.customer?.id {
-            let defaultPaymentMethod = CustomerPaymentOption.defaultPaymentMethod(for: customerID)
+            var defaultPaymentMethodOption: CustomerPaymentOption?
+            // if opted in to the "set as default" feature, try to get default payment method from elements session
+            if configuration.allowsSetAsDefaultPM {
+                guard let customer = elementsSession.customer,
+                  let defaultPaymentMethod = customer.getDefaultOrFirstPaymentMethod() else { return [] }
+                defaultPaymentMethodOption = CustomerPaymentOption.stripeId(defaultPaymentMethod.stripeId)
+            }
+            else {
+                defaultPaymentMethodOption = CustomerPaymentOption.defaultPaymentMethod(for: customerID)
+            }
             if let defaultPMIndex = savedPaymentMethods.firstIndex(where: {
-                $0.stripeId == defaultPaymentMethod?.value
+                $0.stripeId == defaultPaymentMethodOption?.value
             }) {
                 let defaultPM = savedPaymentMethods.remove(at: defaultPMIndex)
                 savedPaymentMethods.insert(defaultPM, at: 0)

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/Saved Payment Method Screen/SavedPaymentOptionsViewController.swift

@@ -103,6 +103,7 @@ class SavedPaymentOptionsViewController: UIViewController {
         let isTestMode: Bool
         let allowsRemovalOfLastSavedPaymentMethod: Bool
         let allowsRemovalOfPaymentMethods: Bool
+        let allowsSetAsDefaultPM: Bool
     }
 
     // MARK: - Internal Properties
@@ -216,6 +217,7 @@ class SavedPaymentOptionsViewController: UIViewController {
     }
     weak var delegate: SavedPaymentOptionsViewControllerDelegate?
     var appearance = PaymentSheet.Appearance.default
+    var elementsSession: STPElementsSession
 
     // MARK: - Private Properties
     private var selectedViewModelIndex: Int?
@@ -311,6 +313,7 @@ class SavedPaymentOptionsViewController: UIViewController {
         paymentSheetConfiguration: PaymentSheet.Configuration,
         intent: Intent,
         appearance: PaymentSheet.Appearance,
+        elementsSession: STPElementsSession,
         cbcEligible: Bool = false,
         analyticsHelper: PaymentSheetAnalyticsHelper,
         delegate: SavedPaymentOptionsViewControllerDelegate? = nil
@@ -320,6 +323,7 @@ class SavedPaymentOptionsViewController: UIViewController {
         self.paymentSheetConfiguration = paymentSheetConfiguration
         self.intent = intent
         self.appearance = appearance
+        self.elementsSession = elementsSession
         self.cbcEligible = cbcEligible
         self.delegate = delegate
         self.analyticsHelper = analyticsHelper
@@ -363,7 +367,9 @@ class SavedPaymentOptionsViewController: UIViewController {
             savedPaymentMethods: savedPaymentMethods,
             customerID: configuration.customerID,
             showApplePay: configuration.showApplePay,
-            showLink: configuration.showLink
+            showLink: configuration.showLink,
+            allowsSetAsDefaultPM: configuration.allowsSetAsDefaultPM,
+            customer: elementsSession.customer
         )
 
         collectionView.reloadData()
@@ -437,9 +443,19 @@ class SavedPaymentOptionsViewController: UIViewController {
 
     /// Creates the list of viewmodels to display in the "saved payment methods" carousel e.g. `["+ Add", "Apple Pay", "Link", "Visa 4242"]`
     /// - Returns defaultSelectedIndex: The index of the view model that is the default e.g. in the above list, if "Visa 4242" is the default, the index is 3.
-    static func makeViewModels(savedPaymentMethods: [STPPaymentMethod], customerID: String?, showApplePay: Bool, showLink: Bool) -> (defaultSelectedIndex: Int, viewModels: [Selection]) {
+    static func makeViewModels(savedPaymentMethods: [STPPaymentMethod], customerID: String?, showApplePay: Bool, showLink: Bool, allowsSetAsDefaultPM: Bool, customer: ElementsCustomer?) -> (defaultSelectedIndex: Int, viewModels: [Selection]) {
         // Get the default
-        let defaultPaymentMethod = CustomerPaymentOption.defaultPaymentMethod(for: customerID)
+        var defaultPaymentMethodOption: CustomerPaymentOption?
+        // if opted in to the "set as default" feature, try to get default payment method from elements session
+        if allowsSetAsDefaultPM {
+           if let customer = customer,
+              let defaultPaymentMethod = customer.getDefaultOrFirstPaymentMethod() {
+               defaultPaymentMethodOption = CustomerPaymentOption.stripeId(defaultPaymentMethod.stripeId)
+           }
+        }
+        else {
+            defaultPaymentMethodOption = CustomerPaymentOption.defaultPaymentMethod(for: customerID)
+        }
 
         // Transform saved PaymentMethods into view models
         let savedPMViewModels = savedPaymentMethods.compactMap { paymentMethod in
@@ -460,7 +476,7 @@ class SavedPaymentOptionsViewController: UIViewController {
         let firstPaymentMethodIsLink = !showApplePay && showLink
         let defaultIndex = firstPaymentMethodIsLink ? 2 : 1
 
-        let defaultSelectedIndex = viewModels.firstIndex(where: { $0 == defaultPaymentMethod }) ?? defaultIndex
+        let defaultSelectedIndex = viewModels.firstIndex(where: { $0 == defaultPaymentMethodOption }) ?? defaultIndex
         return (defaultSelectedIndex, viewModels)
     }
 }

StripePaymentSheet/StripePaymentSheet/Source/PaymentSheet/ViewControllers/PaymentSheetFlowControllerViewController.swift

@@ -206,11 +206,13 @@ class PaymentSheetFlowControllerViewController: UIViewController, FlowController
                 isCVCRecollectionEnabled: false,
                 isTestMode: configuration.apiClient.isTestmode,
                 allowsRemovalOfLastSavedPaymentMethod: PaymentSheetViewController.allowsRemovalOfLastPaymentMethod(elementsSession: elementsSession, configuration: configuration),
-                allowsRemovalOfPaymentMethods: elementsSession.allowsRemovalOfPaymentMethodsForPaymentSheet()
+                allowsRemovalOfPaymentMethods: elementsSession.allowsRemovalOfPaymentMethodsForPaymentSheet(),
+                allowsSetAsDefaultPM: configuration.allowsSetAsDefaultPM
             ),
             paymentSheetConfiguration: configuration,
             intent: intent,
             appearance: configuration.appearance,
+            elementsSession: elementsSession,
             cbcEligible: elementsSession.isCardBrandChoiceEligible,
             analyticsHelper: analyticsHelper
         )