public class TestInvoke : MonoBehaviour, IPointerDownHandler, IPointerUpHandler, IPointerClickHandler, IPointerEnterHandler, IPointerExitHandler
{
    public void OnPointerDown(PointerEventData eventData)
    {
        Debug.LogFormat("[OnPointerDown]pointerPress:{0}", eventData.pointerPress); //這個時候還是空的
 

        Debug.LogFormat("[OnPointerDown]selectedObject:{0}", eventData.selectedObject);
    }

    public void OnPointerUp(PointerEventData eventData)
    {
        Debug.LogFormat("[OnPointerUp]pointerPress:{0}", eventData.pointerPress);
        Debug.LogFormat("[OnPointerUp]selectedObject:{0}", eventData.selectedObject);
    }

    public
 
 void OnPointerClick(PointerEventData eventData)
    {
        Debug.LogFormat("[OnPointerClick]pointerPress:{0}", eventData.pointerPress);
        Debug.LogFormat("[OnPointerClick]selectedObject:{0}", eventData.selectedObject);
    }

    public void OnPointerEnter(PointerEventData eventData)
    {
        Debug.LogFormat("[OnPointerEnter]pointerPress:{0}"
 
, eventData.pointerPress);//這個時候還是空的
        Debug.LogFormat("[OnPointerEnter]selectedObject:{0}", eventData.selectedObject);//這個時候還是空的
    }

    public void OnPointerExit(PointerEventData eventData)
    {
        Debug.LogFormat("[OnPointerExit]pointerPress:{0}", eventData.pointerPress);//這個時候已經空了
        Debug.LogFormat("[OnPointerExit]selectedObject:{0}", eventData.selectedObject);
    }
}

通過繼承幾個點選相關的介面，來打日誌看看，點選響應物件何時才能訪問到

• pointerPress：顧名思義，發生了press才會訪問到，所以在OnPointerEnter、OnPointerExit、OnPointerDown的時候是訪問不到的。
• selectedObject：沒有press這個限制，所以只有OnPointerEnter才訪問不到。
  感覺這些介面表達的含義是，在事件發生時的前一刻。