【iOS 开发】AFNetworking 网络请求失败后通过 N

最近在修改一个网络请求的 bug 时，由于一直请求失败，所以在寻找具体失败原因的时候，了解了一下请求失败的错误返回 NSError ，发现原来可以通过 NSError 中的 code 属性来判断请求失败的具体原因，就在这里记录顺便分享一下。

判断方法

通过判断 NSError 中的 code 错误码属性，可以判断具体失败原因，下面以 NSURLErrorTimedOut 请求超时为例。

/* 开始请求 */
[manager POST:url parameters:parameters progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
    
    NSLog(@"网络请求成功！");
    
} failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
    
    NSLog(@"网络请求失败！");
    if (error.code == NSURLErrorTimedOut) {
        
        NSLog(@"网络请求超时！");
    }
}];

错误码

这里给出苹果提供的所有网络请求的错误码，可以根据不同错误码来给出不同的错误提示以及给出相应的操作，想具体了解每个错误码对应什么意思可以自行查询一下官方文档。

/*!
    @enum NSURL-related Error Codes
    @abstract Constants used by NSError to indicate errors in the NSURL domain
*/
NS_ENUM(NSInteger)
{
    NSURLErrorUnknown =             -1,
    NSURLErrorCancelled =           -999,
    NSURLErrorBadURL =              -1000,
    NSURLErrorTimedOut =            -1001,
    NSURLErrorUnsupportedURL =          -1002,
    NSURLErrorCannotFindHost =          -1003,
    NSURLErrorCannotConnectToHost =         -1004,
    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,
    NSURLErrorAppTransportSecurityRequiresSecureConnection NS_ENUM_AVAILABLE(10_11, 9_0) = -1022,
    NSURLErrorFileDoesNotExist =        -1100,
    NSURLErrorFileIsDirectory =         -1101,
    NSURLErrorNoPermissionsToReadFile =     -1102,
    NSURLErrorDataLengthExceedsMaximum NS_ENUM_AVAILABLE(10_5, 2_0) =   -1103,
    NSURLErrorFileOutsideSafeArea API_AVAILABLE(macosx(10.12.4), ios(10.3), watchos(3.2), tvos(10.2)) = -1104,
    
    // SSL errors
    NSURLErrorSecureConnectionFailed =      -1200,
    NSURLErrorServerCertificateHasBadDate =     -1201,
    NSURLErrorServerCertificateUntrusted =  -1202,
    NSURLErrorServerCertificateHasUnknownRoot = -1203,
    NSURLErrorServerCertificateNotYetValid =    -1204,
    NSURLErrorClientCertificateRejected =   -1205,
    NSURLErrorClientCertificateRequired =   -1206,
    NSURLErrorCannotLoadFromNetwork =       -2000,
    
    // Download and file I/O errors
    NSURLErrorCannotCreateFile =        -3000,
    NSURLErrorCannotOpenFile =          -3001,
    NSURLErrorCannotCloseFile =         -3002,
    NSURLErrorCannotWriteToFile =       -3003,
    NSURLErrorCannotRemoveFile =        -3004,
    NSURLErrorCannotMoveFile =          -3005,
    NSURLErrorDownloadDecodingFailedMidStream = -3006,
    NSURLErrorDownloadDecodingFailedToComplete =-3007,

    NSURLErrorInternationalRoamingOff NS_ENUM_AVAILABLE(10_7, 3_0) =         -1018,
    NSURLErrorCallIsActive NS_ENUM_AVAILABLE(10_7, 3_0) =                    -1019,
    NSURLErrorDataNotAllowed NS_ENUM_AVAILABLE(10_7, 3_0) =                  -1020,
    NSURLErrorRequestBodyStreamExhausted NS_ENUM_AVAILABLE(10_7, 3_0) =      -1021,
    
    NSURLErrorBackgroundSessionRequiresSharedContainer NS_ENUM_AVAILABLE(10_10, 8_0) = -995,
    NSURLErrorBackgroundSessionInUseByAnotherProcess NS_ENUM_AVAILABLE(10_10, 8_0) = -996,
    NSURLErrorBackgroundSessionWasDisconnected NS_ENUM_AVAILABLE(10_10, 8_0)= -997,
};

其实 NSError 还有很多别的错误码，这里只给出网络请求相关的，其他的以后遇到了再记录下来吧。

将来的你，一定会感激现在拼命的自己，愿自己与读者的开发之路无限美好。

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