预期效果：方便、简单调用，能够定位具体的请求并cancel；
思路：类A做具体的请求事件，类B调用类A处理一些业务逻辑：网络或者数据的加工等。

定义类A：QYNetwork 处理具体的请求

• 单列模式，方便调用

+ (instancetype)sharedInstance {
    static dispatch_once_t onceToken;
    static QYNetwork *sharedInstance = nil;
    dispatch_once(&onceToken, ^{
        sharedInstance = [[QYNetwork alloc] init];
    });
    return sharedInstance;
}

• 发起请求

- (NSInteger)callGETWithParams:(NSDictionary *)params
                    methodName:(NSString *)methodName
                       success:(CallBackBlock)success
                          fail:(CallBackBlock)fail {
    __block NSURLSessionDataTask *dataTask = nil;
    
    kWeakSelf(self);
    dataTask = [self.sessionManager GET:methodName parameters:params progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
        kStrongSelf(self);
        
        ///请求完成---移除
        [self.dispatchTable removeObjectForKey:@([dataTask taskIdentifier])];
        
        [self processingResponseObject:responseObject success:success fail:fail];
    } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
        kStrongSelf(self);
        
        [self.dispatchTable removeObjectForKey:@([dataTask taskIdentifier])];
        
        [self processingError:error fail:fail];
    }];
    
    self.dispatchTable[@([dataTask taskIdentifier])] = dataTask;
    return dataTask.taskIdentifier;
}

以task的taskIdentifier作为键保存task，方便针对单个的请求进行cancel，请求完成后remove掉；在请求回调里面进行数据的解析和错误的预处理；

///对API返回的数据进行初始判断
- (void)processingResponseObject:(id)responseObject
                         success:(CallBackBlock)success
                            fail:(CallBackBlock)fail {
    
    NSDictionary *json = [NSJSONSerialization JSONObjectWithData:responseObject options:kNilOptions error:nil];
    
    //TODO:解析code，返回具体数据，具体业务具体处理
    NSInteger code = [json[@"code"] integerValue];
    if (code == 200) {
        !success ?: success(code, json);
    }else {
        !fail ?: fail(code,json[@"message"]);
    }
}

///处理错误事件
- (void)processingError:(NSError *)error
                   fail:(CallBackBlock)fail {
    //TODO:提示
    if (error.code == NSURLErrorTimedOut) {
        //超时
        !fail ?: fail(error.code,@"超时");
    }else if (error.code == NSURLErrorCancelled){
        //取消

    }else if (error.code == NSURLErrorNetworkConnectionLost){
        //网络
        !fail ?: fail(error.code,@"无网络");
    }
    //...
}

• 请求cancel,根据tast的taskIdentifier取消task

- (void)cancelRequestWithRequestID:(NSNumber *)requestID {
   NSURLSessionDataTask *requestOperation = self.dispatchTable[requestID];
   [requestOperation cancel];
   [self.dispatchTable removeObjectForKey:requestID];
}

定义类QYNetManager 让上层调用

• 单列模式，方便调用

+ (instancetype)sharedInstance {
    static dispatch_once_t onceToken;
    static QYNetManager *sharedInstance = nil;
    dispatch_once(&onceToken, ^{
        sharedInstance = [[QYNetManager alloc] init];
    });
    return sharedInstance;
}

• 定义请求的类型：get、post...
• 网络的监听，AFNetWorking自带，这里用RealReachability
• 上层的调用,返回task的taskIdentifier，业务层可以自处理

- (NSInteger)loadDataWithParameters:(NSDictionary *)parameters
                               path:(NSString *)path
                         methodType:(QYRequestType)methodType
                            success:(successBlock)success
                            failure:(failureBlock)failure {
    NSInteger requestId = 0;
    
    if ([self isReachability]) {//网络状态
        switch (methodType) {
            case QYRequestType_GET:
                QYCallAPI(GET,requestId);
                break;
                
            case QYRequestType_POST:
                QYCallAPI(POST,requestId);
                break;
                
            default:
                break;
        }
    }
    
    return requestId;
}

定义的宏：

#define QYCallAPI(REQUEST_METHOD, REQUEST_ID)                                                   \
{                                                                                               \
REQUEST_ID = [[QYNetwork sharedInstance] call##REQUEST_METHOD##WithParams:parameters methodName:path success:^(NSInteger code,id responseObject) {                                                          \
success(responseObject);\
} fail:^(NSInteger code,id responseObject) {                                                                                 \
failure(responseObject);\
}];                                                                                         \
[self.requestIdList addObject:@(REQUEST_ID)];                                               \
}

Demo