Using IComparer for fast sorting on listbox

ListCollectionView allows to sort listbox in wpf to sort.  You bind the listbox to the instance of ListCollectionView.

View.SortDescriptions.Add(new SortDescription(){ PropertyName = columnName,ListSortDirection.Descending});

The above technique uses reflection to sort the ListCollectionView so if you have a large data collection , this can be very slow. 

For faster sorting you can use CustomSort. 

var sortComparer = new UserComparer ()

View.CustomSort = sortComparer;

Classes
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public abstract class SortComparer : IComparer

    {

        public  string SortColumn;

        public ListSortDirection Direction;

        public abstract int Compare(object x, object y);

    }

    public class UserComparer : SortComparer

    {

        public override int Compare(object x, object y)

        {

            var tx = (User)x;

            var ty = (User)y;

            int ret = 0;

            switch (SortColumn)

            {

                case "UserName":

                    {

                        ret = Direction == ListSortDirection.Ascending ? tx.UserName.CompareTo(ty.UserName) : ty.UserName.CompareTo(tx.UserName);

                        break;

                    }

            }

            return ret;

        }

    }