Store last selected payment method

Example/BasicIntegrationUITests/BasicIntegrationUITests.swift

@@ -173,5 +173,66 @@ class BasicIntegrationUITests: XCTestCase {
         waitToAppear(errorButton)
         errorButton.tap()
     }
+
+    func testPaymentOptionsDefault() {
+        // Note that the example backend creates a new Customer every time you start the app
+        // A STPPaymentOptionsVC w/o a selected card...
+        let app = XCUIApplication()
+        disableAddressEntry(app)
+        selectItems(app)
+        let buyNowButton = app.buttons["Buy Now"]
+        buyNowButton.tap()
+        let tablesQuery = app.tables
+        let payFromButton = tablesQuery.otherElements.containing(.staticText, identifier:"Pay from").children(matching: .button).element
+        payFromButton.tap()
 
+        // ...preselects Apple Pay by default
+        let applePay = tablesQuery.cells["Apple Pay"]
+        waitToAppear(applePay)
+        XCTAssertTrue(applePay.isSelected)
+
+        // Selecting another payment method...
+        let visa = tablesQuery.cells["Visa Ending In 3220"]
+        visa.tap()
+
+        // ...and resetting the PaymentOptions VC...
+        // Note that STPPaymentContext clears its cache and refetches every time it's initialized, which happens whenever CheckoutViewController is pushed on
+        app.navigationBars["Checkout"].buttons["Products"].tap()
+        buyNowButton.tap()
+        payFromButton.tap()
+
+        // ...should keep the 3220 card selected
+        XCTAssertTrue(visa.isSelected)
+        XCTAssertFalse(applePay.isSelected)
+
+        // Reselecting Apple Pay...
+        applePay.tap()
+
+        // ...and resetting the PaymentOptions VC...
+        app.navigationBars["Checkout"].buttons["Products"].tap()
+        buyNowButton.tap()
+        payFromButton.tap()
+
+        // ...should keep Apple Pay selected
+        XCTAssertTrue(applePay.isSelected)
+        XCTAssertFalse(visa.isSelected)
+
+        // Selecting another payment method...
+        visa.tap()
+
+        // ...and logging out...
+        app.navigationBars["Checkout"].buttons["Products"].tap()
+        app.navigationBars["Emoji Apparel"].buttons["Settings"].tap()
+        app.tables.children(matching: .cell).element(boundBy: 16).staticTexts["Log out"].tap()
+        app.navigationBars["Settings"].buttons["Done"].tap()
+
+        // ...and going back to PaymentOptionsVC...
+        buyNowButton.tap()
+        payFromButton.tap()
+
+        // ..should not retain the visa default
+        waitToAppear(applePay)
+        XCTAssertTrue(applePay.isSelected)
+        XCTAssertFalse(visa.isSelected)
+    }
 }

Stripe.xcodeproj/project.pbxproj

@@ -1924,6 +1924,7 @@
 		B64763B222FE193800C01BC0 /* STPSetupIntentLastSetupError.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = STPSetupIntentLastSetupError.h; path = PublicHeaders/STPSetupIntentLastSetupError.h; sourceTree = "<group>"; };
 		B64763B322FE193800C01BC0 /* STPSetupIntentLastSetupError.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = STPSetupIntentLastSetupError.m; sourceTree = "<group>"; };
 		B64763B822FE1AF700C01BC0 /* STPSetupIntentLastSetupErrorTest.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = STPSetupIntentLastSetupErrorTest.m; sourceTree = "<group>"; };
+		B65D7C632384ACDD000C6D34 /* STPCustomerContext+Private.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "STPCustomerContext+Private.h"; sourceTree = "<group>"; };
 		B664D64722B800AF00E6354B /* STPThreeDSButtonCustomization.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = STPThreeDSButtonCustomization.m; sourceTree = "<group>"; };
 		B664D64A22B8034D00E6354B /* STPThreeDSCustomization+Private.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "STPThreeDSCustomization+Private.h"; sourceTree = "<group>"; };
 		B664D64D22B8085900E6354B /* STPThreeDSUICustomization.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = STPThreeDSUICustomization.m; sourceTree = "<group>"; };
@@ -3152,6 +3153,7 @@
 		F1728CF41EAAA457002E0C29 /* PaymentContext */ = {
 			isa = PBXGroup;
 			children = (
+				B65D7C632384ACDD000C6D34 /* STPCustomerContext+Private.h */,
 				04E39F5A1CECFAFD00AF3B96 /* STPPaymentContext+Private.h */,
 			);
 			name = PaymentContext;

Stripe/PublicHeaders/STPPaymentOptionsViewController.h

@@ -103,11 +103,13 @@ NS_ASSUME_NONNULL_BEGIN
 
 /**
  The Stripe ID of a payment method to display as the default pre-selected option.
- 
+
  Customer doesn't have a default payment method property, but you can store one
  (in its metadata, for example) and set this property accordingly.
 
  @note Setting this after the view controller's view has loaded has no effect.
+ @note This class automatically saves the Stripe ID of the last selected payment method using NSUserDefaults
+ and displays it as the default pre-selected option.  Settting this value overrides that behavior.
  */
 @property (nonatomic, copy, nullable) NSString *defaultPaymentMethod;
 
@@ -160,6 +162,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
+#pragma mark - STPPaymentOptionsViewControllerDelegate
+
 /**
  An `STPPaymentOptionsViewControllerDelegate` responds when a user selects a 
  payment option from (or cancels) an `STPPaymentOptionsViewController`. In both 

Stripe/STPCustomerContext+Private.h

@@ -0,0 +1,20 @@
+//
+//  STPCustomerContext+Private.h
+//  Stripe
+//
+//  Created by Yuki Tokuhiro on 11/19/19.
+//  Copyright © 2019 Stripe, Inc. All rights reserved.
+//
+
+#import <Stripe/Stripe.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface STPCustomerContext ()
+
+- (void)saveLastSelectedPaymentMethodIDForCustomer:(nullable NSString *)paymentMethodID completion:(nullable STPErrorBlock)completion;
+
+- (void)retrieveLastSelectedPaymentMethodIDForCustomerWithCompletion:(void (^)(NSString * _Nullable, NSError * _Nullable))completion;
+@end
+
+NS_ASSUME_NONNULL_END

Stripe/STPCustomerContext.m

@@ -7,6 +7,7 @@
 //
 
 #import "STPCustomerContext.h"
+#import "STPCustomerContext+Private.h"
 
 #import "STPAPIClient+Private.h"
 #import "STPCustomer+Private.h"
@@ -17,6 +18,9 @@
 #import "STPPaymentMethodCardWallet.h"
 #import "STPDispatchFunctions.h"
 
+/// Stores the key we use in NSUserDefaults to save a dictionary of Customer id to their last selected payment method ID
+static NSString *const kLastSelectedPaymentMethodDefaultsKey = @"com.stripe.lib:STPStripeCustomerToLastSelectedPaymentMethodKey";
+
 static NSTimeInterval const CachedCustomerMaxAge = 60;
 
 @interface STPCustomerContext ()
@@ -255,4 +259,46 @@ - (void)listPaymentMethodsForCustomerWithCompletion:(STPPaymentMethodsCompletion
     }];
 }
 
+- (void)saveLastSelectedPaymentMethodIDForCustomer:(NSString *)paymentMethodID completion:(nullable STPErrorBlock)completion {
+    [self.keyManager getOrCreateKey:^(STPEphemeralKey *ephemeralKey, NSError *retrieveKeyError) {
+        if (retrieveKeyError) {
+            if (completion) {
+                stpDispatchToMainThreadIfNecessary(^{
+                    completion(retrieveKeyError);
+                });
+            }
+            return;
+        }
+
+        NSMutableDictionary<NSString *, NSString *>* customerToDefaultPaymentMethodID = [[[NSUserDefaults standardUserDefaults] dictionaryForKey:kLastSelectedPaymentMethodDefaultsKey] mutableCopy] ?: [NSMutableDictionary new];
+        NSString *customerID = ephemeralKey.customerID;
+
+        customerToDefaultPaymentMethodID[customerID] = [paymentMethodID copy];
+        [[NSUserDefaults standardUserDefaults] setObject:customerToDefaultPaymentMethodID forKey:kLastSelectedPaymentMethodDefaultsKey];
+        if (completion) {
+            stpDispatchToMainThreadIfNecessary(^{
+                completion(nil);
+            });
+        }
+    }];
+}
+
+- (void)retrieveLastSelectedPaymentMethodIDForCustomerWithCompletion:(void (^)(NSString * _Nullable, NSError * _Nullable))completion {
+    [self.keyManager getOrCreateKey:^(STPEphemeralKey *ephemeralKey, NSError *retrieveKeyError) {
+        if (retrieveKeyError) {
+            if (completion) {
+                stpDispatchToMainThreadIfNecessary(^{
+                    completion(nil, retrieveKeyError);
+                });
+            }
+            return;
+        }
+
+        NSDictionary<NSString *, NSString *>* customerToDefaultPaymentMethodID = [[NSUserDefaults standardUserDefaults] dictionaryForKey:kLastSelectedPaymentMethodDefaultsKey];
+        stpDispatchToMainThreadIfNecessary(^{
+            completion(customerToDefaultPaymentMethodID[ephemeralKey.customerID], nil);
+        });
+    }];
+}
+
 @end

Stripe/STPPaymentContext.m

@@ -11,7 +11,7 @@
 
 #import "PKPaymentAuthorizationViewController+Stripe_Blocks.h"
 #import "STPAddCardViewController+Private.h"
-#import "STPCustomerContext.h"
+#import "STPCustomerContext+Private.h"
 #import "STPDispatchFunctions.h"
 #import "STPPaymentConfiguration+Private.h"
 #import "STPPaymentContext+Private.h"
@@ -157,8 +157,18 @@ - (void)retryLoading {
                         [strongSelf2.loadingPromise fail:error];
                         return;
                     }
-                    STPPaymentOptionTuple *paymentTuple = [STPPaymentOptionTuple tupleFilteredForUIWithPaymentMethods:paymentMethods selectedPaymentMethod:strongSelf2.defaultPaymentMethod configuration:strongSelf2.configuration];
-                    [strongSelf2.loadingPromise succeed:paymentTuple];
+
+                    if (self.defaultPaymentMethod == nil && [strongSelf2.apiAdapter isKindOfClass:[STPCustomerContext class]]) {
+                        // Retrieve the last selected payment method saved by STPCustomerContext
+                        [((STPCustomerContext *)strongSelf2.apiAdapter) retrieveLastSelectedPaymentMethodIDForCustomerWithCompletion:^(NSString * _Nullable paymentMethodID, NSError * _Nullable __unused _) {
+                            __strong typeof(self) strongSelf3 = weakSelf;
+                            STPPaymentOptionTuple *paymentTuple = [STPPaymentOptionTuple tupleFilteredForUIWithPaymentMethods:paymentMethods selectedPaymentMethod:paymentMethodID configuration:strongSelf3.configuration];
+                            [strongSelf3.loadingPromise succeed:paymentTuple];
+                        }];
+                    } else {
+                        STPPaymentOptionTuple *paymentTuple = [STPPaymentOptionTuple tupleFilteredForUIWithPaymentMethods:paymentMethods selectedPaymentMethod:self.defaultPaymentMethod configuration:strongSelf2.configuration];
+                        [strongSelf2.loadingPromise succeed:paymentTuple];
+                    }
                 });
             }];
         });

Stripe/STPPaymentOptionTableViewCell.m

@@ -78,6 +78,7 @@ - (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(nulla
             [self.titleLabel.centerYAnchor constraintEqualToAnchor:self.contentView.centerYAnchor],
 
         ]];
+        self.isAccessibilityElement = YES;
     }
     return self;
 }
@@ -120,6 +121,13 @@ - (void)configureWithPaymentOption:(id<STPPaymentOption>)paymentOption theme:(ST
     // Checkmark icon
     self.checkmarkIcon.tintColor = theme.accentColor;
     self.checkmarkIcon.hidden = !selected;
+
+    // Accessibility
+    if (selected) {
+        self.accessibilityTraits |= UIAccessibilityTraitSelected;
+    } else {
+        self.accessibilityTraits &= ~UIAccessibilityTraitSelected;
+    }
 
     [self setNeedsLayout];
 }

Stripe/STPPaymentOptionTuple.m

@@ -71,9 +71,9 @@ + (instancetype)tupleFilteredForUIWithPaymentMethods:(NSArray<STPPaymentMethod *
     }
 
     return [[self class] tupleWithPaymentOptions:paymentOptions
-                                    selectedPaymentOption:selectedPaymentMethod
-                                        addApplePayOption:configuration.applePayEnabled
-                                        additionalOptions:configuration.additionalPaymentOptions];
+                           selectedPaymentOption:selectedPaymentMethod
+                               addApplePayOption:configuration.applePayEnabled
+                               additionalOptions:configuration.additionalPaymentOptions];
 }
 
 @end

Stripe/STPPaymentOptionsViewController.m

@@ -13,6 +13,7 @@
 #import "STPCard.h"
 #import "STPColorUtils.h"
 #import "STPCoreViewController+Private.h"
+#import "STPCustomerContext+Private.h"
 #import "STPDispatchFunctions.h"
 #import "STPLocalizationUtils.h"
 #import "STPPaymentActivityIndicatorView.h"
@@ -80,7 +81,15 @@ - (instancetype)initWithConfiguration:(STPPaymentConfiguration *)configuration
             if (error) {
                 [promise fail:error];
             } else {
-                STPPaymentOptionTuple *paymentTuple = [STPPaymentOptionTuple tupleFilteredForUIWithPaymentMethods:paymentMethods selectedPaymentMethod:self.defaultPaymentMethod configuration:configuration];
+                NSString *defaultPaymentMethod = self.defaultPaymentMethod;
+                if (defaultPaymentMethod == nil && [apiAdapter isKindOfClass:[STPCustomerContext class]]) {
+                    // Retrieve the last selected payment method saved by STPCustomerContext
+                    [((STPCustomerContext *)apiAdapter) retrieveLastSelectedPaymentMethodIDForCustomerWithCompletion:^(NSString * _Nullable paymentMethodID, NSError * _Nullable __unused _) {
+                        STPPaymentOptionTuple *paymentTuple = [STPPaymentOptionTuple tupleFilteredForUIWithPaymentMethods:paymentMethods selectedPaymentMethod:paymentMethodID configuration:configuration];
+                        [promise succeed:paymentTuple];
+                    }];
+                }
+                STPPaymentOptionTuple *paymentTuple = [STPPaymentOptionTuple tupleFilteredForUIWithPaymentMethods:paymentMethods selectedPaymentMethod:defaultPaymentMethod configuration:configuration];
                 [promise succeed:paymentTuple];
             }
         });
@@ -166,6 +175,19 @@ - (void)updateAppearance {
 }
 
 - (void)finishWithPaymentOption:(id<STPPaymentOption>)paymentOption {
+    BOOL isReusablePaymentMethod = [paymentOption isKindOfClass:[STPPaymentMethod class]] && ((STPPaymentMethod *)paymentOption).type == STPPaymentMethodTypeCard;
+
+    if ([self.apiAdapter isKindOfClass:[STPCustomerContext class]]) {
+        if (isReusablePaymentMethod) {
+            // Save the payment method
+            STPPaymentMethod *paymentMethod = (STPPaymentMethod *)paymentOption;
+            [((STPCustomerContext *)self.apiAdapter) saveLastSelectedPaymentMethodIDForCustomer:paymentMethod.stripeId completion:nil];
+        } else {
+            // The customer selected something else (like Apple Pay)
+            [((STPCustomerContext *)self.apiAdapter) saveLastSelectedPaymentMethodIDForCustomer:nil completion:nil];
+        }
+    }
+
     if ([self.delegate respondsToSelector:@selector(paymentOptionsViewController:didSelectPaymentOption:)]) {
         [self.delegate paymentOptionsViewController:self didSelectPaymentOption:paymentOption];
     }