我希望你用C#写一个在unity中使用的自定义计时器不能继承MonoBehaviour

好的，以下是一个基于C#的自定义计时器，可以在Unity中使用，但不继承于MonoBehaviour。

using System.Collections.Generic;
using UnityEngine;

public class CustomTimer
{
    private float currentTime;
    private float duration;
    private bool isLooping;
    private bool isPaused;
    private bool isStarted;
    private List<System.Action> callbacks;

    public CustomTimer(float duration, bool isLooping = false)
    {
        this.duration = duration;
        this.isLooping = isLooping;
        this.callbacks = new List<System.Action>();
    }

    public void Start()
    {
        this.isStarted = true;
        this.isPaused = false;
        this.currentTime = 0f;
    }

    public void Stop()
    {
        this.isStarted = false;
        this.isPaused = false;
        this.currentTime = 0f;
    }

    public void Pause()
    {
        this.isPaused = true;
    }

    public void Resume()
    {
        this.isPaused = false;
    }

    public void AddCallback(System.Action callback)
    {
        this.callbacks.Add(callback);
    }

    public void RemoveCallback(System.Action callback)
    {
        this.callbacks.Remove(callback);
    }

    public void Update()
    {
        if (!this.isStarted || this.isPaused)
        {
            return;
        }

        this.currentTime += Time.deltaTime;

        if (this.currentTime >= this.duration)
        {
            foreach (var callback in this.callbacks)
            {
                callback();
            }

            if (this.isLooping)
            {
                this.currentTime -= this.duration;
            }
            else
            {
                this.isStarted = false;
            }
        }
    }
}

使用方式如下：

CustomTimer timer = new CustomTimer(2f, true);
timer.AddCallback(() => {
    Debug.Log("Timer callback");
});
timer.Start();

void Update() {
    timer.Update();
}

这个计时器可以设置持续时间和是否循环，并可以添加回调函数。在Update()函数中调用Update()方法即可。