BindablePicker.cs question

[michaelb4]

In the OnSelectedItemChanged event, should the SelectedIndex be set to -1 when SelectedItem == null?

private static void OnSelectedItemChanged(BindableObject bindable, object oldValue, object newValue)
{
BindablePicker picker = (BindablePicker)bindable;
picker.SelectedItem = newValue;
if (picker.ItemsSource != null && picker.SelectedItem != null)
{
int count = 0;
foreach (object obj in picker.ItemsSource)
{
if (obj == picker.SelectedItem)
{
picker.SelectedIndex = count;
break;
}
count++;
}
}
}

For instance:
else picker.SelectedIndex = -1;

Thank you for your consideration.