Unity 实现按下按钮替换按钮的图片

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

public class BTManager_Active: MonoBehaviour {
    public static BTManager_Active Instance;
    //------------------单例模式------------------------------------------------//
    // Use this for initialization
    //------------------定义数组------------------------------------------------//
    public GameObject[] BiaoTiBtn;                      //标题按钮
  
    public bool isFMJZ = true;
    public bool isSSLC = true;
    public bool isSJQH = true;
    public bool isYCCK = true;

    public Sprite BTReturnImage;
    public Sprite BTStartImage;
 

    void Awake()
    {
        //单例模式
        Instance = this;

    }

    void Start()
    {

    }

    // Update is called once per frame
    void Update()
    {

    }

    public void Reset_BTBool()
    {
        isFMJZ = true;
        isSSLC = true;
        isSJQH = true;
        isYCCK = true;
    }
    //----------------------------------------------标题按钮的显示和隐藏--------------------------------------------//
    /// <summary>
    ///标题按钮的显示和隐藏
    /// </summary>
    /// <param name="isActive"></param>
    public void BTActive(bool isActive)
    {
        for (int i = 0; i < BiaoTiBtn.Length; i++)
        {
            BiaoTiBtn[i].gameObject.SetActive(isActive);
        }
    }

    //-----------------------------------------------标题的缩放控制------------------------------------------------//
    /// <summary>
    /// 
    /// </summary>
    public void BT_FMJZ()  //BiaoTiBtn[0]
    {
        if (isFMJZ == true)
        {
            //播放标题缩回的动画
            AniManager.Instance.BTAniPlay(AniManager.Instance.BTAni[0], "BT_FMJZ_Ani");
            //替换btn上的Image
            BiaoTiBtn[0].GetComponent<Image>().sprite = BTReturnImage;
            isFMJZ = false;
        }
        else
        {
            //播放标题展开的动画
            AniManager.Instance.BTAniReturnPlay(AniManager.Instance.BTAni[0], "BT_FMJZ_Ani");
            //替换btn上的Image
            BiaoTiBtn[0].GetComponent<Image>().sprite = BTStartImage;
            isFMJZ = true;
        }
    }
    /// <summary>
    /// 
    /// </summary>
    public void BT_SSLC()  //BiaoTiBtn[1]
    {
        if (isSSLC == true)
        {
            //播放标题缩回的动画
            AniManager.Instance.BTAniPlay(AniManager.Instance.BTAni[1], "BT_SSLC_Ani");
            BiaoTiBtn[1].GetComponent<Image>().sprite = BTReturnImage;
            isSSLC = false;
        }
        else
        {
            //播放标题展开的动画
            AniManager.Instance.BTAniReturnPlay(AniManager.Instance.BTAni[1], "BT_SSLC_Ani");
            BiaoTiBtn[1].GetComponent<Image>().sprite = BTStartImage;
            isSSLC = true;
        }
    }
    /// <summary>
    /// 
    /// </summary>
    public void BT_SJQH()  //BiaoTiBtn[2]
    {
        if (isSJQH == true)
        {
            //播放标题缩回的动画
            AniManager.Instance.BTAniPlay(AniManager.Instance.BTAni[2], "BT_SJQH_Ani");
            BiaoTiBtn[2].GetComponent<Image>().sprite = BTReturnImage;
            isSJQH = false;
        }
        else
        {
            //播放标题展开的动画
            AniManager.Instance.BTAniReturnPlay(AniManager.Instance.BTAni[2], "BT_SJQH_Ani");
            BiaoTiBtn[2].GetComponent<Image>().sprite = BTStartImage;
            isSJQH = true;
        }
    }
    /// <summary>
    /// 
    /// </summary>
    public void BT_YCCK()  //BiaoTiBtn[3]
    {
        if (isYCCK == true)
        {
            //播放标题缩回的动画
            AniManager.Instance.BTAniPlay(AniManager.Instance.BTAni[3], "BT_YCCK_Ani");
            BiaoTiBtn[3].GetComponent<Image>().sprite = BTReturnImage;
            isYCCK = false;
        }
        else
        {
            //播放标题展开的动画
            AniManager.Instance.BTAniReturnPlay(AniManager.Instance.BTAni[3], "BT_YCCK_Ani");
            BiaoTiBtn[3].GetComponent<Image>().sprite = BTStartImage;
            isYCCK = true;
        }
    }