03、三种简单的计时器

1、计时器在游戏中的使用次数很多，以下是三种简单的计时器写法

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

public class Timer : MonoBehaviour
{
    private Text textTime;
    private int second = 20;

    private void Awake()
    {
        textTime = this.GetComponent<Text>();
    }
    private void Update()
    {
        //Timer_01();
       // Timer_02();
    }

    //第一种方式的计时器
    private float nextTimer_1 = 1;   //下次修改时间
    private float nextTime_1 = 1;    //一次间隔是多少
    private void Timer_01()
    {
        if (nextTimer_1 <= Time.time)
        {
            //到了1秒
            second--;
            if (second >= 0)
            {
                textTime.text = string.Format("{0:d2}:{1:d2}", (int)second / 60, (int)second % 60);
                nextTimer_1 += nextTime_1;  //将计时器当前的存储加上程序运行的时间
            }
        }
    }

    //第二种方式的计时器
    private float nextTime_2_1 = 0;
    private float nextTime_2_2 = 1;  //时间间隔
    private void Timer_02()
    {
        nextTime_2_1 += Time.deltaTime;
        if (nextTime_2_1 >= nextTime_2_2)
        {
            //到了1秒了
            second--;
            if (second >= 0)
            {
                textTime.text = string.Format("{0:d2}:{1:d2}", second / 60, second % 60);
                nextTime_2_1 = 0;
            }
        }
    }

    //第三种是使用InvokeRepeating，来指定起始时间，重复调用方法的间隔
    private void Start()
    {
        InvokeRepeating("Timer_03", 0, 1);
    }
    private void Timer_03()
    {
        second--;
        if(second<=0)
        {
            CancelInvoke("Timer_03");   //如果时间为0了，则就要终止循环调用了
        }
        textTime.text = string.Format("{0:d2}:{1:d2}", second / 60, second % 60);
    }
}