oc-网络请求

网络请求是编程的重要一步份
///

• (void)getDataWith: (NSString *)URLString{

  NSURL * url = [NSURL URLWithString:URLString];
  //网络请求对象
  NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:url];
  NSURLSession * session = [NSURLSession sharedSession];
  //请求任务
  NSURLSessionDataTask * dataTask = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
  //主线程
  dispatch_async(dispatch_get_main_queue(), ^{
  //解析json数据
  if (!error) {
  id result = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
  NSLog(@"result = %@",result);
  for (NSDictionary * songDic in result) {
  Song * song = [[Song alloc]init];
  [song setValuesForKeysWithDictionary:songDic];
  [self.songArr addObject:song];
  }
  //刷新tableview的数据
  [self.tableView reloadData];
  } else {
  NSLog(@"error : %@",error);
  }
  });
  }];
  //手动开启任务
  [dataTask resume]
  }
  ///