这个是官方的文档，下面结合协程简单的测试下

using UnityEngine;
using System.Collections;

public class MyYield : MonoBehaviour {

    // Use this for initialization
    bool isCango = true;
	void Start () {
        // StartCoroutine(GoandWait());
        StartCoroutine(testFrame());
	}
    IEnumerator testFrame() {
         yield return new WaitForEndOfFrame();
        // yield return null;
        //yield return new WaitForFixedUpdate();
        Debug.LogError("this is update over");
    }
    IEnumerator GoandWait() {
        while (true) {
            yield return new WaitForSeconds(3f);
           

            float startTime = Time.time;
            float endTime = startTim