block-AFHTTPRequestOperation獲取responseObject

AFHTTPRequestOperation獲取responseObject

@property (nonatomic, strong) NSDictionary *dic;

#pragma mark - 從網絡獲取json數據

• (NSDictionary *)getJsonData{

  NSString *urlStr = @"http://api.worldweatheronline.com/free/v2/weather.ashx?q=chengdu&num_of_days=7&format=json&tp=6&key=5fc3a5873e9bdb5bbf8116ea3aac5";
  NSURL *url = [NSURL URLWithString:urlStr];
  NSURLRequest *request = [NSURLRequest requestWithURL:url];

  //使用AFNetworking解析json數據
  //實例化http操作請求
  AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

  //設定解析器
  operation.responseSerializer = [AFJSONResponseSerializer serializer];

  //下載數據並解析
  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

  [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
  
      //json數據全局化
      self.dic = (NSDictionary *)responseObject;
  
  } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
      NSLog(@"解析出錯：%@",error);
  }];
  

  });
  [operation start];

  return self.dic;
  }
  我已經提升dic成屬性了，為什麼返回的self.dic為空？
  個人猜想是跟 block 執行時期有關，希望能有人指點迷津，謝謝！

最佳回答：

你這是創建一個分線程去下載數據，但是下載完成後沒有刷新主線程。你這邊返回的self.dic是肯定是空得。應該是下載完成（下載成功或者失敗都是完成）後再返回dic，這才比較合理。