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

public class SelectTraget : MonoBehaviour
{
    public Button Btn_Left;
    public Button Btn_Right;
    public Transform ReferencePoint;//参考位置(显示区域中央)
    public Transform Content;//被移动物体 
    private int index;
    public int Indexer
    {
        get 
        { 
            return index;
        }
        set 
        {
            if (value < 0)
            {
                print("最左");
                index = 0;
            }
            else if (value > Content.transform.childCount-1)
            {
                print("最右");
                index = Content.transform.childCount - 1;
            }
            else
            {
                index = value;
                //移动
                float A = Content.GetChild(index).position.x - ReferencePoint.position.x;//差值;
                Content.DOMoveX(Content.position.x - A, 1f);
            }
            print(index);
        }
    }
    
    public void Awake()
    {
        Btn_Left = transform.Find("Btn_Left").GetComponent<Button>();
        Btn_Right = transform.Find("Btn_Right").GetComponent<Button>();

        Btn_Back = transform.parent.Find("Btn_Back").GetComponent<Button>();
        Btn_Sure = transform.parent.Find("Btn_Sure").GetComponent<Button>();
        ReferencePoint = transform.Find("ReferencePoint");

        Content = transform.Find("Viewport/Content");
        

        Btn_Left.onClick.AddListener(InputLeft);
        Btn_Right.onClick.AddListener(InputRight);
    }

    public void InputLeft()
    {
        print("Left");
        Indexer--;
    }
    public void InputRight()
    {
        print("Right");
        Indexer++;
    }
}

脚本挂在Scroll View 上
其它节点如下图

运行效果