List 排序

List<int> nList= new List<int>(); 
new List<string>(sortStrings).ForEach(e => { nList.Add(int.Parse(e)); }); 
Item.Sort( (a, b) => { return nList.FindIndex(s => s == a.AttributeId) - nList.FindIndex(s => s == b.AttributeId); }); 

return list.OrderByDescending(p =>
                {
                    if (true)
                    {
                       return -1;
                    }
                    return 0;
                }).ToList();