void Start()
{
enemyCountText = GameObject.Find("EnemyCountText").GetComponent <Text>();
enemySpawn = GameObject.Find("EnemySpawn").GetComponent <EnemySpawn>();
}
//预留接口
public void Init(EnemySpawn spawn, float speed, Player player)
{
this.spawn = spawn;
this.speed = speed;
this.player = player;
}