UGUI脚本添加Btn回调的方法

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;

//对添加这个脚本的对象添加EventTrigger组件
[RequireComponent(typeof(UnityEngine.EventSystems.EventTrigger))]
public class BtnPointClick : MonoBehaviour {

    Button btn;
    EventTrigger.Entry beginClick;
    EventTrigger.Entry pointClick;
    EventTrigger.Entry endClick;
    EventTrigger eventTrigger;

    void Awake()
    {
        btn = this.GetComponent<Button>();
        eventTrigger = this.GetComponent<EventTrigger>();

        beginClick = new EventTrigger.Entry();
        pointClick = new EventTrigger.Entry();
        endClick = new EventTrigger.Entry();
    }
	void Start () {
        beginClick.eventID = EventTriggerType.PointerDown;
        pointClick.eventID = EventTriggerType.PointerClick;
        endClick.eventID = EventTriggerType.PointerUp;
        //注册事件回调
        beginClick.callback = new EventTrigger.TriggerEvent();
        pointClick.callback = new EventTrigger.TriggerEvent();
        endClick.callback = new EventTrigger.TriggerEvent();
        //添加事件监听
        beginClick.callback.AddListener(BeginClickEvent);
        pointClick.callback.AddListener(PointClickEvent);
        endClick.callback.AddListener(EndClickEvent);

        //添加事件到委托事件
        eventTrigger.triggers.Add(beginClick);
        eventTrigger.triggers.Add(pointClick);
        eventTrigger.triggers.Add(endClick);
    }

    /// <summary>
    /// 开始点击的事件回调
    /// </summary>
    /// <param name="data"></param>
    private void BeginClickEvent(BaseEventData data)
    {
        Debug.Log("开始点击");
    }
    /// <summary>
    /// 点击的事件回调
    /// </summary>
    /// <param name="data"></param>
    private void PointClickEvent(BaseEventData data)
    {
        Debug.Log("点击事件");
    }
    /// <summary>
    /// 鼠标抬起的事件回调
    /// </summary>
    /// <param name="data"></param>
    private void EndClickEvent(BaseEventData data)
    {
        Debug.Log("鼠标抬起事件");
    }
}