1 + (AFHTTPRequestOperation *)requestSellerWithCompletion:(requestFinishedCompletionBlock)successBlock 2 { 3     AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager]; 4  5     AFHTTPRequestOperation * operation = [manager GET:kRequestSellerURL parameters:nil success:^(AFHTTPRequestOperation *operation, id responSEObject) { 6   7         if (operation.isCancelled) { 8          //若果operation已經被cancel了，則不對返回數據進行處理 9             NSLog(@"operation is Canceled");10         }else{11      //如果沒有cancel 掉，則進行正常的數據解析12             NSArray *sellerArray = [MTLJSONAdapter modelsOfClass:[Seller class] fromJSONArray:responseObject[@"data"] error:nil];13             if (successBlock) {14               //  NSLog(@"current operation count is %d",[manager.operationQueue operations].count);15                 successBlock(sellerArray);16             }17         }18 19 20     } failure:^(AFHTTPRequestOperation *operation, NSError *error) {21 22     }];

然后在for循環里這么做.for (int i = 1; i <= 10; i++) {        if (operation) {            [operation cancel];        }      operation = [Seller requestSellerWithCompletion:^(id object) {            NSLog(@"finished download %d",i);        }];    }