GridView gridView =GetVisualChild<GridView>(listView) as GridView;

  public static T GetVisualChild<T>(Visual parent) where T : Visual
        {
            T child = default(T);

            int numVisuals = VisualTreeHelper.GetChildrenCount(parent);
            for (int i =  0 ; i < numVisuals; i++)
            {
                Visual v = (Visual)VisualTreeHelper.GetChild(parent, i);
                child = v as T;
                if (child == null)
                {
                    child = GetVisualChild<T>(v);
                }
                if (child != null)
                {
                    break;
                }
            }

            return child;
        }