手動添加EventTrigger的事件固然方便，但是不利于以后的修改，所以用代碼添加是很有必要的。

起初使用的時候是參考了各家博主的代碼，都大致相似，就直接拿來。但是當我要在一個EventTrigger下添加多個事件的時候，代碼就冗余了，干脆封成一個方法，用起來方便，主要是不用費心思給那些臨時變量起名字了。

代碼如下：

    /// <summary>
    /// 添加EventTrigger的監聽事件
    /// </summary>
    /// <param name="obj">添加監聽的對象</param>
    /// <param name="eventID">添加的監聽類型</param>
    /// <param name="action">觸發方法</param>
    private void AddTriggersListener(GameObject obj, EventTriggerType eventID, UnityAction<BaseEventData> action)
    {
        EventTrigger trigger = obj.GetComponent<EventTrigger>();
        if (trigger == null)
        {
            trigger = obj.AddComponent<EventTrigger>();
        }

        if (trigger.triggers.Count == 0)
        {
            trigger.triggers = new List<EventTrigger.Entry>();
        }
        
        UnityAction<BaseEventData> callback = new UnityAction<BaseEventData>(action);
        EventTrigger.Entry entry = new EventTrigger.Entry();
        entry.eventID = eventID;
        entry.callback.AddListener(callback);
        trigger.triggers.Add(entry);
    }

使用示例：

//播放進度條EventTrigger監聽
AddTriggersListener(sliderProgressBar.gameObject, EventTriggerType.PointerEnter, OnVideoPointerEnter);
AddTriggersListener(sliderProgressBar.gameObject, EventTriggerType.PointerExit, OnVideoPointerExit);
AddTriggersListener(sliderProgressBar.gameObject, EventTriggerType.PointerClick, OnVideoPointerClick);
AddTriggersListener(sliderProgressBar.gameObject, EventTriggerType.BeginDrag, OnVideoBeginDrag);
AddTriggersListener(sliderProgressBar.gameObject, EventTriggerType.EndDrag, OnVideoEndDrag);