计时器管理类

using UnityEngine;  
using System.Collections;  
using System;  

public class TimerManager : MonoBehaviour   
{  

    private static TimerManager m_instance = null;  
    public static TimerManager Instance { get { return m_instance; } }  

    void Awake()  
    {  
        m_instance = this;  
    }  
    // Use this for initialization  
    void Start () {  

    }  

    // Update is called once per frame  
    void Update () {  

    }  

    public void GetTimer(int second,MyTimer.Mode mode,MyTimer.TimesUp TimesUpDelegate,MyTimer.PerSecond PerSecondDelegate=null)  
    {  
  GameObject Timer = Instantiate(Resources.Load("Prefabs/Time/MyTimer")) as GameObject;  
        Timer.transform.parent = transform;  

        Timer.GetComponent().SetTimer(second);  
        Timer.GetComponent().SetMode(mode);  
        Timer.GetComponent().SetTimesUpDelegate(TimesUpDelegate);  
        Timer.GetComponent().SetPerSecondDelegate(PerSecondDelegate);  
        Timer.GetComponent().StartTimer();  
    }  
   public String GetTimeBySecond(float seconds)  
    {  
        return DateTime.Parse(DateTime.Now.ToString("00:00:00")).AddSeconds(seconds).ToString("HH:mm:ss");  
    }  
}

倒计时类

using UnityEngine;  
using System.Collections;  

public class MyTimer : MonoBehaviour {  

    public enum Mode  
    {  
        PerSecond,  
        Once,  
        Loop  
    }  

    public float TotalSeconds;  
    public Mode m_mode;  
    public delegate void TimesUp();  
    public TimesUp timesUp = null;  

    public delegate void PerSecond(float timesLeft);  
    public PerSecond perSecond = null;  

    int m_leaveSeconds;  
  void Awake()  
    {  

    }  

    // Use this for initialization  
    void Start () {  

    }  

    // Update is called once per frame  
    void Update () {  

    }  
  public void StartTimer()  
    {  
        switch (m_mode)  
        {  
            case Mode.PerSecond:  
                StartCoroutine(TimerBeginPerSocond());  
                break;  
            case Mode.Once:  
                StartCoroutine(TimerBegin());  
                break;  
            case Mode.Loop:  
                break;  
        }  

    }  
  public void SetTimer(int seconds)  
    {  
        TotalSeconds = seconds;  
    }  

    public void SetMode(Mode mode)  
    {  
        m_mode = mode;  
    }  

    public void SetTimesUpDelegate(TimesUp del)  
    {  
        timesUp = del;  
    }  
 public void SetPerSecondDelegate(PerSecond del)  
    {  
        perSecond = del;  
    }  

    IEnumerator TimerBegin()  
    {  
        yield return new WaitForSeconds(TotalSeconds);  
        timesUp();  
        Destroy(gameObject);  
    }  
  IEnumerator TimerBeginPerSocond()  
    {  
        yield return new WaitForSeconds(1f);  
        if ((TotalSeconds--) > 0)  
        {  
            perSecond(TotalSeconds);  
            StartCoroutine(TimerBeginPerSocond());  
        }  
        else  
        {  
            timesUp();  
            Destroy(gameObject);  
        } 
    }  
}

分别挂在两个预制上。管理类预先加载到场景中

public void CreateTimerManager()  
{  
    GameObject TimerManager = GameObject.Instantiate(Resources.Load("Prefabs/Manager/TimerManager")) as GameObject;  
    TimerManager.name = "TimerManager";  
}

每请求一个定时器，调管理类函数，选择模式和返回的回调。可选每秒返回，每次返回，循环也可以但是暂时没这个需求