以前的旧框架，以前的项目已经正常运行，这次访问iOS付款时，服务器出现了21002错误。这个问题让我头疼了一天。
原因简单正常iOS内部购买，苹果的收据，由客户端提供base64编码后，直接发送给服务器，然后服务器要求苹果的对账服务器进行验证。只需按照苹果的要求组装即可json字符串。
网上关于设置 content_type = "application/json; charset=utf-8"，或者换空间 其实和这个21002半毛钱没关系。
据我的测试可得知，content_type设置与否并不重要，空间被替换为 号码也是客户端和服务器之间的传输协议。http请求可以替换，但如果使用socket连接，这根本不是问题。
这是唯一可能存在问题的地方base64数据块有问题。base64编码数据被破坏，可能是base64编码内容被破坏。
后一种情况听起来很奇怪。但事实上，这就是我这次遇到的。为什么？Unity IAP将插件发送给客户端的是Json字符串！收据就是这个Json部分已经编码了。客户端再次编码整个字符串，完全不同。
{"Store":"AppleAppStore","TransactionID":"2000000039643941","Payload":"MIITvQYJKoZIhvcNAQcCoIITrjCCE6oCAQExCzAJBgUrDgMCGgUAMIIDXgYJKoZIhvcNAQcBoIIDTwSCA0sxggNHMAoCAQgCAQEEAhYAMAoCARQCAQEEAgwAMAsCAQECAQEEAwIBADALAgEDAgEBBAMMATAwCwIBCwIBAQQDAgEAMAsCAQ8CAQEEAwIBADALAgEQAgEBBAMCAQAwCwIBGQIBAQQDAgEDMAwCAQoCAQEEBBYCNCswDAIBDgIBAQQEAgIAnjANAgENAgEBBAUCAwJLHDANAgETAgEBBAUMAzEuMDAOAgEJAgEBBAYCBFAyNTYwGAIBBAIBAgQQGPbrdE kSdWjkiiQITX29TAbAgEAAgEBBBMMEVByb2R1Y3Rpb25TYW5kYm94MBwCAQUCAQEEFKsl44zcXE0xasiszPzJ/c8xkJGBMB4CAQwCAQEEFhYUMjAyMi0wNC0yNFQwNToyNzo1N1owHgIBEgIBAQQWFhQyMDEzLTA4LTAxVDA3OjAwOjAwWjAoAgECAgEBBCAMHmNvbS53b293YXlnYW1lcy5vbmVwZXJjZW50LmlvczAwAgEHAgEBBCi9PlIOqxn1OinWJJ574 GdEl2cHzM6UE6 iRMPDPPC001AYaF9QZVRMD4CAQYCAQEENjlvoEjy8RZrVJjJ1HXGjAre7PTJ8a8E6AneOQYppRF3qbnZ7t0wd1GRVEACKfLCHvD..."}这里可以看到，Json字符串的Payload部分是收据，还经过Base64编码。所以。只需读出这部分并发送给服务器。
另外，说到21002，还有一种可能，那就是服务器和苹果对账服务器的连接不能是长连接。每次请求完成后关闭。如果使用那种Keep Alive如果试图与苹果对账服务器保持长连接，您将得到21002的随机错误。
如果您想验证您的代码是否有问题，您可以直接使用以下收据（已经存在）base64编码)试试。如果能得到解密字符串，代码就成功了。
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