AFURLResponseSerialization 的作用是對請求返回的數(shù)據(jù)進行序列化

它有一個序列化的基類AFHTTPResponseSerializer勘畔，有六個不同的序列化的類繼承于它

• AFJSONResponseSerializer JSON格式數(shù)據(jù)響應(yīng)
• AFXMLParserResponseSerializer iOS端XML數(shù)據(jù)解析響應(yīng)
• AFXMLDocumentResponseSerializerMAC OS端XML數(shù)據(jù)解析響應(yīng)
• AFPropertyListResponseSerializerplist格式數(shù)據(jù)解析響應(yīng)
• AFImageResponseSerializer圖片數(shù)據(jù)解析響應(yīng)
• AFCompoundResponseSerializer復(fù)合式數(shù)據(jù)解析響應(yīng)

在序列化之前申钩，有一個必要的工作肯适，那就是校驗響應(yīng)是否有效饥悴，在基類AFHTTPResponseSerializer里面提供了一個核心方法，主要是是校驗響應(yīng)內(nèi)容的類型和狀態(tài)碼

- (BOOL)validateResponse:(NSHTTPURLResponse *)response
                    data:(NSData *)data
                   error:(NSError * __autoreleasing *)error
{
    BOOL responseIsValid = YES;
    NSError *validationError = nil;

    if (response && [response isKindOfClass:[NSHTTPURLResponse class]]) {
        //如果返回的內(nèi)容類型是不支持的類型，拋出錯誤
        if (self.acceptableContentTypes && ![self.acceptableContentTypes containsObject:[response MIMEType]] &&
            !([response MIMEType] == nil && [data length] == 0)) {

            if ([data length] > 0 && [response URL]) {
                NSMutableDictionary *mutableUserInfo = [@{
                                                          NSLocalizedDescriptionKey: [NSString stringWithFormat:NSLocalizedStringFromTable(@"Request failed: unacceptable content-type: %@", @"AFNetworking", nil), [response MIMEType]],
                                                          NSURLErrorFailingURLErrorKey:[response URL],
                                                          AFNetworkingOperationFailingURLResponseErrorKey: response,
                                                        } mutableCopy];
                if (data) {
                    mutableUserInfo[AFNetworkingOperationFailingURLResponseDataErrorKey] = data;
                }

                validationError = AFErrorWithUnderlyingError([NSError errorWithDomain:AFURLResponseSerializationErrorDomain code:NSURLErrorCannotDecodeContentData userInfo:mutableUserInfo], validationError);
            }

            responseIsValid = NO;
        }
        //如果返回的狀態(tài)碼不是200~299哈恰，拋出錯誤
        if (self.acceptableStatusCodes && ![self.acceptableStatusCodes containsIndex:(NSUInteger)response.statusCode] && [response URL]) {
            NSMutableDictionary *mutableUserInfo = [@{
                                               NSLocalizedDescriptionKey: [NSString stringWithFormat:NSLocalizedStringFromTable(@"Request failed: %@ (%ld)", @"AFNetworking", nil), [NSHTTPURLResponse localizedStringForStatusCode:response.statusCode], (long)response.statusCode],
                                               NSURLErrorFailingURLErrorKey:[response URL],
                                               AFNetworkingOperationFailingURLResponseErrorKey: response,
                                       } mutableCopy];

            if (data) {
                mutableUserInfo[AFNetworkingOperationFailingURLResponseDataErrorKey] = data;
            }

            validationError = AFErrorWithUnderlyingError([NSError errorWithDomain:AFURLResponseSerializationErrorDomain code:NSURLErrorBadServerResponse userInfo:mutableUserInfo], validationError);

            responseIsValid = NO;
        }
    }

    if (error && !responseIsValid) {
        *error = validationError;
    }

    return responseIsValid;
}

其他都是序列化操作晶通，還有初始化方法璃氢，實現(xiàn)NSSecureCoding和NSCopying協(xié)議，這些都是大同小異狮辽，值得一提的是一個圖片加載的分類一也，主要作用是對圖片的解壓，這里可以仔細看下bang's blog喉脖，里面做了比較詳細解釋