yichael_smartbow/Assets/BowArrow/Scripts/Game/StartTimer.cs

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

public class StartTimer : MonoBehaviour
{
    int time = 3;

    void Start()
    {
        this.ChangeTime();
    }

    void ChangeTime() 
    {
        this.transform.localScale = new Vector3(1, 1, 1);
        this.GetComponent<Text>().text = this.time > 0 ? this.time.ToString() : "开始";
        this.transform.DOScale(new Vector3(0.75f, 0.75f, 1), 0.8f).OnComplete(delegate() {
            this.time--;
            if (this.time >= 0) 
            {
                this.ChangeTime();
            } else {
                Destroy(this.gameObject);
            }
        });
    }
}