Microsoft.Phone.Controls.ListPicker.OnSelectedItemsChanged C# (CSharp) Method

        private void OnSelectedItemsChanged(IList oldValue, IList newValue)
        {
            UpdateSummary(newValue);

            // Fire SelectionChanged event
            var handler = SelectionChanged;
            if (null != handler)
            {
                IList removedItems = new List<object>();
                if (null != oldValue)
                {
                    foreach (object o in oldValue)
                    {
                        if (null == newValue || !newValue.Contains(o))
                        {
                            removedItems.Add(o);
                        }
                    }
                }
                IList addedItems = new List<object>();
                if (null != newValue)
                {
                    foreach (object o in newValue)
                    {
                        if (null == oldValue || !oldValue.Contains(o))
                        {
                            addedItems.Add(o);
                        }
                    }
                }

                handler(this, new SelectionChangedEventArgs(removedItems, addedItems));
            }
        }