タッチしたらスプライトの色が変わる

touch.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using System;
public class touch : MonoBehaviour
{
    public Image image;
    [SerializeField]
    Color btnColor1 = Color.red;
    [SerializeField]
    Color btnColor2 = Color.blue;
    bool btnChangeFlag = true;



    public void onButton()
    {
        btnChangeFlag = !btnChangeFlag;
        image.color= btnChangeFlag ? btnColor1 : btnColor2;

    }
}