AFNetworking3.0 如何取消单个网络请求

NSURL *URL = [NSURLURLWithString:@http];

    AFHTTPSessionManager *manager = [AFHTTPSessionManagermanager];

    NSURLSessionDataTask *task = [managerGET:URL.absoluteStringparameters:nilprogress:nilsuccess:^(NSURLSessionTask *task,id responseObject) {

        NSLog(@"JSON: %@", responseObject);

    } failure:^(NSURLSessionTask *operation,NSError *error) {

        NSLog(@"Error: %@", error);

    }];

//取消单个请求

    [task cancel];

//取消当前所有

    [manager.operationQueuecancelAllOperations];