iOS 请求状态码

  kCFURLErrorUnknown   = -998,

  kCFURLErrorCancelled = -999,

  kCFURLErrorBadURL    = -1000,

  kCFURLErrorTimedOut  = -1001,

  kCFURLErrorUnsupportedURL = -1002,

  kCFURLErrorCannotFindHost = -1003,

  kCFURLErrorCannotConnectToHost    = -1004,

  kCFURLErrorNetworkConnectionLost  = -1005,

  kCFURLErrorDNSLookupFailed        = -1006,

  kCFURLErrorHTTPTooManyRedirects   = -1007,

  kCFURLErrorResourceUnavailable    = -1008,

  kCFURLErrorNotConnectedToInternet = -1009,

  kCFURLErrorRedirectToNonExistentLocation = -1010,

  kCFURLErrorBadServerResponse             = -1011,

  kCFURLErrorUserCancelledAuthentication   = -1012,

  kCFURLErrorUserAuthenticationRequired    = -1013,

  kCFURLErrorZeroByteResource        = -1014,

  kCFURLErrorCannotDecodeRawData     = -1015,

  kCFURLErrorCannotDecodeContentData = -1016,

  kCFURLErrorCannotParseResponse     = -1017,

  kCFURLErrorInternationalRoamingOff = -1018,

  kCFURLErrorCallIsActive               = -1019,

  kCFURLErrorDataNotAllowed             = -1020,

  kCFURLErrorRequestBodyStreamExhausted = -1021,

  kCFURLErrorFileDoesNotExist           = -1100,

  kCFURLErrorFileIsDirectory            = -1101,

  kCFURLErrorNoPermissionsToReadFile    = -1102,

  kCFURLErrorDataLengthExceedsMaximum   = -1103,