ios - UISearchDisplayController 文本更改滞后

Question

我正在尝试在我的 Parse 数据库中搜索用户列表。为此，我有一个搜索栏 Controller 和表格 View 。当用户搜索时，搜索结果似乎落后了一个字母。例如，如果我搜索“Be”，它会显示所有以“B”而不是“Be”开头的名字，当我搜索“Ben”时，它会显示所有以“Be”开头的用户。

这是我的 textDidChange 方法:

-(void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText{

NSString *string = searchText;
string = string.lowercaseString;
if(string.length>0){
        PFUser *currentUser = [PFUser currentUser];
        PFQuery *query = [PFQuery queryWithClassName:@"_User"];
        [query whereKey:@"name_lower" containsString:string];
        [query whereKey:@"username" notEqualTo:currentUser.username];
        [query orderByAscending:@"name_lower"];
        [query setLimit:1000];
        [query findObjectsInBackgroundWithBlock:^(NSArray *array,NSError *error){
            if(!error){
                results = [[NSArray alloc]initWithArray:array];

                [_mainTableView reloadData];

            }else{
                [ProgressHUD showError:@"Error Searching"];
            }
        }];
}else{
    NSLog(@"NO RESULTS");
    results = nil;
    [_mainTableView reloadData];
}

}

然后在我的 cellforrow 中:

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];
if (cell == nil) cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"cell"];


    PFUser *user = results[indexPath.row];
    [user fetchIfNeeded];



    cell.textLabel.text = [NSString stringWithFormat:@"%@ - @%@",user[@"name"],user[@"username"]];
    cell.detailTextLabel.text = user[@"university"];
}

Answer 1

嘿，试着像这样设置约束:

[查询 whereKey:@"name_lower"hasPrefix:string];


代替

[查询 whereKey:@"name_lower"containsString:string];


毕竟我会这样做:

-(void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText{

      NSString *string = searchText;
      string = string.lowercaseString;
      if(string.length>0){
          PFQuery *query = [PFUser query];
          [query whereKey:@"name_lower" hasPrefix:string];
          [query whereKey:@"username" notEqualTo:[[PFUser currentUser] username]];
          [query orderByAscending:@"name_lower"];
          [query setLimit:1000];
          [query findObjectsInBackgroundWithBlock:^(NSArray *array,NSError *error){
               if(!error){
                    results = array;

                    [_mainTableView reloadData];

               } else {
                    [ProgressHUD showError:@"Error Searching"];
               }
           }];
      } else {
          NSLog(@"NO RESULTS");
          results = nil;
          [_mainTableView reloadData];
      }
}