void ConstrainToItemsView()
{
var itemsViewWidth = ItemsView.Width;
var itemsViewHeight = ItemsView.Height;
if (itemsViewHeight < 0 || itemsViewWidth < 0)
{
ItemsViewLayout.UpdateConstraints(CollectionView.Bounds.Size);
return;
}
ItemsViewLayout.UpdateConstraints(new CGSize(itemsViewWidth, itemsViewHeight));
}