按降序排列的 OrderBy Observable 集合 - UWP

Question

I can order by my observable collection using below code. How can I order by it in descending order?

  RollNoArray _mainItems = new  RollNoArray();
  _mainItems.SubItemsList = new ObservableCollection<SubItems>();
  //..adding data to _mainItems.SubItemsList here
  _mainItems.SubItemsList = new ObservableCollection<SubItems>
 (from i in _mainItems.SubItemsList orderby i.num select i);// order by num

Answer 1

使用 Linq OrderByDescending而不是 OrderBy：

_mainItems.SubItemsList.OrderByDescending(i => i.num).ToList();