Unity中使用协程实现倒计时功能

using UnityEngine;
using System.Collections;

public class ShowNumber : MonoBehaviour {
    private int tmp = 10;
	// Use this for initialization
	void Start () {
        //开启一个协程
        StartCoroutine("changeTime");
	}
    void OnGUI()
    {
        GUILayout.BeginArea(new Rect(100,100,300,100));
        GUILayout.Label("" + tmp, GUILayout.Width(300));
        GUILayout.EndArea();
    }
	
    IEnumerator changeTime()
    {
        while(tmp > 0)
        {
            //暂停一秒
            yield return new WaitForSeconds(1);
            tmp--;
        }
    }
}