iOS开发笔记（5）---- 应用内接入Apple Pay

自2014年苹果秋季发布会至今，Apple Pay推出已将近一年时间，我们对其便利性与安全性也早有耳闻，然而时至今日其使用范围仍然只限美国、英国两地区，对于在中国区的引入，我们只能报以期望。

总体来说，在应用内集成Apple Pay需要两个部分：交易授权与交易处理。交易授权在应用内进行，通过PassKit.framework所提供的接口向用户获取支付授权；而交易处理则需要授权后调用可受理交易的服务器接口，你可以选择某个支付平台来处理交易，或者也可以自己实现交易处理过程，苹果官方比较推荐前者。

准备工作：

在接入Apple Pay之前，首先要申请MerchantID及对应证书。

1. 申请 MerchantID
   登陆MemberCenter,选择Certificates, Identifiers & Profiles；
   在Identifiers下选择Merchant IDs，点击右上角添加按钮添加Merchant ID；
   输入描述信息和标识符(格式为merchant.com.company.productid)，继续至完成即可。
   
2. 本地生成CSR文件，用于请求证书。
   打开钥匙串访问工具，在钥匙串访问下拉菜单选中证书助理-》从证书颁发机构请求证书;
   输入appId邮件地址、名称，选择存储到磁盘，勾选让我指定秘钥对信息；
   秘钥大小选择256位，算法选择ECC。
   
3. 请求证书
   进入MemberCenter，根据之前步骤找到前面申请的Merchant ID；
   在这里可以编辑该项，上传之前生成的CSR文件并生成cer证书文件；
   下载证书文件即可。
   

工程设置

在应用内集成Apple Pay，还需要引用依赖库PassKit.framework，并且在Capability中启用Apple Pay权限（在这里需要配置merchantId）。

到这里我们的准备工作就完成了，接下来开始集成Apple Pay。

创建支付请求

在真正创建支付请求之前，我们应该先对当前的支付环境进行检测，看看当前设备、系统及Apple Pay设置是否满足支付条件。

//检查当前设备是否可以支付
[PKPaymentAuthorizationViewController canMakePayments]

//检查用户是否可进行某种卡的支付，目前仅支持Amex、MasterCard与Visa三种卡
[PKPaymentAuthorizationViewController canMakePaymentsUsingNetworks: @[PKPaymentNetworkAmex, PKPaymentNetworkMasterCard,PKPaymentNetworkVisa]]

在环境检测完成后即可创建支付请求。

• 设置币种、国家码及merchant标识符等基本信息

PKPaymentRequest *request=[PKPaymentRequest new];
request.currencyCode = @"USD";
request.countryCode = @"US";
request.merchantIdentifier = @"merchant.com.example";

• 设置费用项
  在这里可以设置费用的各组成部分及最后结算，包括小计、运费、折扣等项，每一项包含标签字符串和金额两个属性。

//小计
NSDecimalNumber *subtotalAmount = [NSDecimalNumber decimalNumberWithMantissa:1275 exponent:-2 isNegative:NO];
self.subtotal = [PKPaymentSummaryItem summaryItemWithLabel:@"Subtotal" amount:subtotalAmount];

//折扣
NSDecimalNumber *discountAmount = [NSDecimalNumber decimalNumberWithMantissa:200 exponent:-2 isNegative:YES];
self.discount = [PKPaymentSummaryItem summaryItemWithLabel:@"Discount" amount:discountAmount];

// 合计
NSDecimalNumber *totalAmount = [NSDecimalNumber zero];
totalAmount = [totalAmount decimalNumberByAdding:subtotalAmount];
totalAmount = [totalAmount decimalNumberByAdding:discountAmount];
self.total = [PKPaymentSummaryItem summaryItemWithLabel:@"My Company Name" amount:totalAmount];


 //支付请求的支付总结属性是一个数组，数组中的最后一个PKPaymentSummaryItem为合计。
self.summaryItems = @[self.subtotal, self.discount, self.total];
request.paymentSummaryItems = self.summaryItems;

• 设置交易处理参数

//设置支持卡种
request.supportedNetworks = @[PKPaymentNetworkAmex, PKPaymentNetworkMasterCard, PKPaymentNetworkVisa];


// 设置支持的交易处理协议，3DS必须支持，EMV为可选
request.merchantCapabilities = PKMerchantCapability3DS | PKMerchantCapabilityEMV;

• 设置邮寄地址和账单地址

 request.requiredBillingAddressFields = PKAddressFieldEmail;
    request.requiredShippingAddressFields=PKAddressFieldPostalAddress;

    ABRecordRef record = ABPersonCreate();
    CFErrorRef error;
    BOOL success;
    success = ABRecordSetValue(record, kABPersonFirstNameProperty, @"John", &error);
    if (!success) { /* ... handle error ... */ }
    success = ABRecordSetValue(record, kABPersonLastNameProperty, @"Appleseed", &error); if (!success) { /* ... handle error ... */ }
    ABMultiValueRef shippingAddress =
    ABMultiValueCreateMutable(kABMultiDictionaryPropertyType);
    NSDictionary *addressDictionary = @{
                                        (NSString *) kABPersonAddressStreetKey: @"1234 Laurel Street",
                                        (NSString *) kABPersonAddressCityKey: @"Atlanta", (NSString *) kABPersonAddressStateKey: @"GA", (NSString *) kABPersonAddressZIPKey: @"30303" };
    ABMultiValueAddValueAndLabel(shippingAddress,
                                 (__bridge CFDictionaryRef) addressDictionary,
                                 kABOtherLabel,
                                 nil);
    success = ABRecordSetValue(record, kABPersonAddressProperty, shippingAddress,
                               &error);
    if (!success) { /* ... handle error ... */ }
    request.shippingAddress = record;
    CFRelease(shippingAddress);
    CFRelease(record);

• 设置邮寄方式

    NSDecimalNumber *freeAmount = [NSDecimalNumber decimalNumberWithString:@"0.00"];
    PKShippingMethod *freeShipping = [PKShippingMethod summaryItemWithLabel:@"Free Shipping" amount:freeAmount];
    freeShipping.detail = @"Arrives by July 2";
    freeShipping.identifier = @"free";

    NSDecimalNumber *standardAmount = [NSDecimalNumber decimalNumberWithString:@"3.21"];
    PKShippingMethod *standardShipping = [PKShippingMethod summaryItemWithLabel:@"Standard Shipping" amount:standardAmount];
    standardShipping.detail = @"Arrives by June 29";
    standardShipping.identifier = @"standard";

    NSDecimalNumber *expressAmount = [NSDecimalNumber decimalNumberWithString:@"24.63"];
    PKShippingMethod *expressShipping = [PKShippingMethod summaryItemWithLabel:@"Express Shipping" amount:expressAmount];
    expressShipping.detail = @"Ships within 24 hours";
    expressShipping.identifier = @"express";

    request.shippingMethods== @[freeShipping, standardShipping, expressShipping];

到这里，一个支付请求已经创建完成，接下来我们需要用它来创建一个PKPaymentAuthorizationViewController，并通过实现PKPaymentAuthorizationViewController的委托方法来获取授权。

PKPaymentAuthorizationViewController *viewController =
    [[PKPaymentAuthorizationViewController alloc] initWithPaymentRequest:request];
    if (!viewController) { /* ... Handle error ... */ }
    viewController.delegate = self;
    [self presentViewController:viewController animated:YES completion:nil];

实现支付授权委托

实现支付授权的委托，也就是实现PKPaymentAuthorizationViewControllerDelegate协议，这里面有两个必选方法：

//完成授权后的回调方法，这里可以调用server的交易处理接口，并在处理完成后通过completion块通知PKPaymentAuthorizationViewController交易状态
- (void)paymentAuthorizationViewController:(PKPaymentAuthorizationViewController *)controller
                       didAuthorizePayment:(PKPayment *)payment
                                completion:(void (^)(PKPaymentAuthorizationStatus status))completion;


//交易完成后回调方法，这里就可以关掉PKPaymentAuthorizationViewController了
- (void)paymentAuthorizationViewControllerDidFinish:(PKPaymentAuthorizationViewController *)controller;

除此之外，还有三个可选方法：

//选择邮寄地址之后回调，这里可以根据所选地址更改邮寄方式及费用，并通过completion块更新PKPaymentAuthorizationViewController
- (void)paymentAuthorizationViewController:(PKPaymentAuthorizationViewController *)controller
                  didSelectShippingAddress:(ABRecordRef)address
                                completion:(void (^)(PKPaymentAuthorizationStatus status, NSArray *shippingMethods, NSArray *summaryItems))completion;

//选择邮寄方式后回调，这里可以根据所选邮寄方式更新费用信息，并通过completion块更新PKPaymentAuthorizationViewController
- (void)paymentAuthorizationViewController:(PKPaymentAuthorizationViewController *)controller
                   didSelectShippingMethod:(PKShippingMethod *)shippingMethod
                                completion:(void (^)(PKPaymentAuthorizationStatus status, NSArray *summaryItems))completion;

//输完指纹或密码之后，授权支付之前回调
-(void)paymentAuthorizationViewControllerWillAuthorizePayment:(PKPaymentAuthorizationViewController *)controller NS_AVAILABLE_IOS(8_3);

以下为委托方法的部分实现：

-(void)paymentAuthorizationViewController:(PKPaymentAuthorizationViewController *)controller didSelectShippingAddress:(ABRecordRef)address completion:(void (^)(PKPaymentAuthorizationStatus, NSArray *, NSArray *))completion{
    [self updateShippingMethods];
    completion(PKPaymentAuthorizationStatusSuccess,self.shippingMethods,self.summaryItems);
}

-(void)paymentAuthorizationViewController:(PKPaymentAuthorizationViewController *)controller didSelectShippingMethod:(PKShippingMethod *)shippingMethod completion:(void (^)(PKPaymentAuthorizationStatus, NSArray *))completion{

    [self updateSummaryItems:shippingMethod.identifier];
    completion(PKPaymentAuthorizationStatusSuccess,self.summaryItems);

}

-(void)paymentAuthorizationViewController:(PKPaymentAuthorizationViewController *)controller didAuthorizePayment:(PKPayment *)payment completion:(void (^)(PKPaymentAuthorizationStatus))completion{
    //在这里调用服务器处理交易，并获取交易状态
    completion(PKPaymentAuthorizationStatusSuccess);
}

-(void)paymentAuthorizationViewControllerDidFinish:(PKPaymentAuthorizationViewController *)controller{
    [controller dismissViewControllerAnimated:true completion:nil];
}


-(void) updateShippingMethods{
    NSDecimalNumber *freeAmount = [NSDecimalNumber decimalNumberWithString:@"0.00"];
    PKShippingMethod *freeShipping = [PKShippingMethod summaryItemWithLabel:@"Free Shipping" amount:freeAmount];
    freeShipping.detail = @"Arrives by July 2";
    freeShipping.identifier = @"free";

    NSDecimalNumber *standardAmount = [NSDecimalNumber decimalNumberWithString:@"3.21"];
    PKShippingMethod *standardShipping = [PKShippingMethod summaryItemWithLabel:@"Standard Shipping" amount:standardAmount];
    standardShipping.detail = @"Arrives by June 29";
    standardShipping.identifier = @"standard";

    NSDecimalNumber *expressAmount = [NSDecimalNumber decimalNumberWithString:@"24.63"];
    PKShippingMethod *expressShipping = [PKShippingMethod summaryItemWithLabel:@"Express Shipping" amount:expressAmount];
    expressShipping.detail = @"Ships within 24 hours";
    expressShipping.identifier = @"express";

    _shippingMethods= @[freeShipping, standardShipping, expressShipping];
}

-(void) updateSummaryItems:(NSString *)identifier{
    if ([identifier isEqualToString:@""]) {
        return;
    }

    NSDecimalNumber *shippingAmount;
    if ([identifier isEqualToString:@"standard"]) {
        shippingAmount=[NSDecimalNumber decimalNumberWithMantissa:321
                                                         exponent:-2 isNegative:NO];
    }else if ([identifier isEqualToString:@"Express"]) {
        shippingAmount=[NSDecimalNumber decimalNumberWithMantissa:2463
                                                         exponent:-2 isNegative:NO];
    }

    PKPaymentSummaryItem* shipping=[PKPaymentSummaryItem summaryItemWithLabel:@"Shipping"
                                                 amount:shippingAmount];


    NSDecimalNumber *subtotalAmount = [NSDecimalNumber decimalNumberWithMantissa:1275
                                                                        exponent:-2 isNegative:NO];
    PKPaymentSummaryItem* subtotal = [PKPaymentSummaryItem summaryItemWithLabel:@"Subtotal"
                                                                         amount:subtotalAmount];

    NSDecimalNumber *discountAmount = [NSDecimalNumber decimalNumberWithMantissa:200
                                                                        exponent:-2 isNegative:YES];
    PKPaymentSummaryItem* discount = [PKPaymentSummaryItem summaryItemWithLabel:@"Discount"
                                                                         amount:discountAmount];

    NSDecimalNumber *totalAmount = [NSDecimalNumber zero];
    totalAmount = [totalAmount decimalNumberByAdding:subtotalAmount];
    totalAmount = [totalAmount decimalNumberByAdding:discountAmount];
    totalAmount = [totalAmount decimalNumberByAdding:shippingAmount];
    PKPaymentSummaryItem* total = [PKPaymentSummaryItem summaryItemWithLabel:@"Ipaynow"
                                                                      amount:totalAmount];

    _summaryItems=@[subtotal, shipping, discount, total];

}

以上，就是在应用内接入Apple Pay的主要内容。