Я знаю, как это сделать.
private void CheckResultAccordion(IEnumerable<ListSearchResult> results)
{
ResultAccordion.ItemsSource = null;
ResultAccordion.ItemsSource = results;
ResultAccordion.UpdateLayout();
OpenAllAccordionItems(results.Count());
ResultAccordion.Visibility = Visibility.Visible;
}
private void OpenAllAccordionItems(int count)
{
while (count > 1)
{
ResultAccordion.SelectedIndex = count - 1;
count--;
}
}