您可以在此方法后获取应该位于文本字段中的字符串：

You can get the string that is supposed to be in text field after this method:

NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];

那个 neString 你可能会用'用于搜索数据库。

And that neString you probably can use 'as is' for searching the database.

如果您只是想在用户删除textField中的某些字符时获取该事件 - 那么您可以通过以下方式进行检查：

If you just want to get the event when user deletes some characters in textField - then you can check it the following way:

if ([string length] == 0 && range.length > 0)
  //Some characters deleted