统一-无限刷出问题

我几乎已经准备好了我的游戏，我想为我的2D游戏创建无限数量的2D正方形。然而，我使用的下面代码不能无限地生成单个正方形。

using UnityEngine;
using System.Collections;
public class Spawner : MonoBehaviour
{
    private GameObject[] locationsToSpawn;
    private float counter = 0;
    [SerializeField]
    string[] listOfPossibleTags;
    [SerializeField]
    GameObject[] objectToSpawn;
    [SerializeField]
    float timeBetweenSpawns = 3.0f;
    void Start()
    {
        locationsToSpawn = GameObject.FindGameObjectsWithTag("SpawnLocation");
    }
    void Update()
    {
        counter += Time.deltaTime;
        if (counter > timeBetweenSpawns)
        {
            GameObject spawnedObject;
            spawnedObject = Instantiate(objectToSpawn[Random.Range(0, objectToSpawn.Length)], locationsToSpawn[Random.Range(0, locationsToSpawn.Length)].transform.position, Quaternion.identity) as GameObject;
            spawnedObject.gameObject.tag = listOfPossibleTags[Random.Range(0, listOfPossibleTags.Length)];
            counter = 0;
        }
    }
}

同样，我的游戏看起来像下面的图片

那么，我怎么做才能产生无限个数的方块下落呢?我马上就要完成游戏了