unity3d 刷新速率

 using UnityEngine;
 using UnityEngine.UI;

 public class Text : MonoBehaviour {

     public Text t;
     private float rate = 2f;
     private float lastTime = ;

     // Use this for initialization
     void Start () {

         Random.InitState(System.Guid.NewGuid().GetHashCode());

     }

     // Update is called once per frame
     void Update () {
         float time = Time.time;
         if(time - lastTime > rate)
         {
             lastTime = time;
             Text();
         }
     }

     public void Text()
     {
         int random = Random.Range(, );
         t.text = random;
     }
 }