实例化预设体并且获取预设体的各个组件

把要实例化的物体放入Resources文件夹内，然后使用
Resources.Load()方法

 GameObject go = Resources.Load("DialogUI") as GameObject;
        GameObject gameObject = Instantiate(go, Vector3.zero, Quaternion.identity) as GameObject;
        Transform transform = gameObject.transform.GetChild(3).GetChild(0);
        Text text = transform.GetComponent<Text>();
        text.text = "ETAGame";