void Awake()
{
//1. 拿到引用，绑定事件
contentText = transform.Find("Content").GetComponent <Text>();
transform.Find("ButtonOk").GetComponent <Button>().onClick.AddListener(ClickOk);
transform.Find("ButtonCancel").GetComponent <Button>().onClick.AddListener(ClickCancel);
instance = this;
}
void Awake()
{
_instance = this;
txt = transform.Find("Text").GetComponent <Text> ();
}