how can do open and close click in UI.EventSystems

i did a dropdown menu from a youtube tutorial but she shows OnPointerEnter and OnPointerExit. i did one OnPointerClick for open but the function allows once. i want to do twice. when i click it will open, when i click again it will close. how can i do it??

The Script:

using UnityEngine;
using UnityEngine.EventSystems;
using System.Collections;

public class DropDown : MonoBehaviour, IPointerClickHandler, IPointerExitHandler{

	public RectTransform container;
	public bool isOpen;

	// Use this for initialization
	void Start () {
		container = transform.FindChild ("Container").GetComponent<RectTransform> ();
		isOpen = false;
	}
	
	// Update is called once per frame
	void Update () {

		Vector3 scale = container.localScale;
		scale.y = Mathf.Lerp (scale.y, isOpen ? 1 : 0, Time.deltaTime * 12);
		container.localScale = scale;
	}

	public void OnPointerClick(PointerEventData eventData)
	{
		isOpen = true;
	}
	public void OnPointerExit(PointerEventData eventData)
	{
		isOpen = false;
	}
}

public void OnPointerClick(PointerEventData eventData)
{
isOpen = !isOpen;
}