可以去苹果官网查询对应的解释：
https://developer.apple.com/documentation/foundation/1508628-url_loading_system_error_codes

以下罗列对应码：

       NSURLErrorUnknown = -1,
       NSURLErrorCancelled = -999,
       NSURLErrorBadURL = -1000,
       NSURLErrorTimedOut = -1001,
       NSURLErrorUnsupportedURL = -1002,
       NSURLErrorCannotFindHost = -1003,
       NSURLErrorCannotConnectToHost = -1004,
       NSURLErrorDataLengthExceedsMaximum = -1103,
       NSURLErrorNetworkConnectionLost = -1005,
       NSURLErrorDNSLookupFailed = -1006,
       NSURLErrorHTTPTooManyRedirects = -1007,
       NSURLErrorResourceUnavailable = -1008,
       NSURLErrorNotConnectedToInternet = -1009,
       NSURLErrorRedirectToNonExistentLocation = -1010,
       NSURLErrorBadServerResponse = -1011,
       NSURLErrorUserCancelledAuthentication = -1012,
       NSURLErrorUserAuthenticationRequired = -1013,
       NSURLErrorZeroByteResource = -1014,
       NSURLErrorCannotDecodeRawData = -1015,
       NSURLErrorCannotDecodeContentData = -1016,
       NSURLErrorCannotParseResponse = -1017,
       NSURLErrorInternationalRoamingOff = -1018,
       NSURLErrorCallIsActive = -1019,
       NSURLErrorDataNotAllowed = -1020,
       NSURLErrorRequestBodyStreamExhausted = -1021,
       NSURLErrorFileDoesNotExist = -1100,
       NSURLErrorFileIsDirectory = -1101,
       NSURLErrorNoPermissionsToReadFile = -1102,
       NSURLErrorSecureConnectionFailed = -1200,
       NSURLErrorServerCertificateHasBadDate = -1201,
       NSURLErrorServerCertificateUntrusted = -1202,
       NSURLErrorServerCertificateHasUnknownRoot = -1203,
       NSURLErrorServerCertificateNotYetValid = -1204,
       NSURLErrorClientCertificateRejected = -1205,
       NSURLErrorClientCertificateRequired = -1206,
       NSURLErrorCannotLoadFromNetwork = -2000,
       NSURLErrorCannotCreateFile = -3000,
       NSURLErrorCannotOpenFile = -3001,
       NSURLErrorCannotCloseFile = -3002,
       NSURLErrorCannotWriteToFile = -3003,
       NSURLErrorCannotRemoveFile = -3004,
       NSURLErrorCannotMoveFile = -3005,
       NSURLErrorDownloadDecodingFailedMidStream = -3006,
       NSURLErrorDownloadDecodingFailedToComplete = -3007

而 HTTP Status Code 对应的解释，大家自行网上搜索，比如如下链接：
https://baike.baidu.com/item/HTTP%E7%8A%B6%E6%80%81%E7%A0%81/5053660?fromtitle=HTTP%20Status%20Code&fromid=11296236&fr=aladdin