如何获得一颗Visual Tree 的某个控件 WPF

        private T FindVisualChild<T>(DependencyObject obj) where T:DependencyObject        {            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)            {                DependencyObject child = VisualTreeHelper.GetChild(obj, i);                if (child!=null&&child is T)                {                    return child as T;                }                else                {                    T childOfChild = FindVisualChild<T>(child);                    if (childOfChild != null)                        return childOfChild;                }            }            return null;        }