当我使用instantiateViewControllerWithIdentifier时，UIViewController没有成员错误

Question

我正在尝试将得分数据从名为ViewController.swift的主游戏视图控制器传递到另一个名为game_over_vc.swift的视图控制器。故事板ID是game_over_vc。我使用instantiateViewControllerWithIdentifier在游戏结束时转到game_over_vc并显示分数。 game_over_vc.swift中有一个名为score_text的变量，它应该从ViewController.swift中检索数据。但是，我收到一个错误，说明值类型＆＃39; UIViewController＆＃39;没有会员＆＃39; score_text＆＃39;。我哪里出错了？

func game_over () {
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let game_over_vc = storyboard.instantiateViewControllerWithIdentifier("game_over_vc") as UIViewController

    game_over_vc.score_text = String(score) //the error is here

    self.presentViewController(game_over_vc as UIViewController, animated: false, completion: nil)
}