ios - 尝试在其 View 不在窗口层次结构中的 UIViewController 上呈现 GKGameCenterViewController

Question

当用户按下我的 SecondViewController 上的按钮时，我无法显示 Game Center 排行榜(带有得分/最高得分的游戏结束屏幕)。 UIbutton 是 ShowLeaderboard，您将在下面看到它。

我得到的错误是:

Warning: Attempt to present <GKGameCenterViewController: 0x7fb1c88044a0> on <UIViewController: 0x7fb1c2624e90> whose view is not in the window hierarchy!

我曾尝试先关闭该 View ，但无论我做什么，我都无法只显示排行榜 View 。下面是我的 SecondViewController 代码:

import UIKit
import GameKit

class SecondViewController: UIViewController, GKGameCenterControllerDelegate {


@IBOutlet var scoreLabel: UILabel!
@IBOutlet var HighScoreLabel: UILabel!
var receivedString: String = ""
var receivedHighScore: String = ""


override func viewDidLoad() {
    super.viewDidLoad()
    scoreLabel.text = receivedString
    HighScoreLabel.text = receivedHighScore

}


@IBAction func ShowLeaderboard(sender: UIButton) {
    dismissViewControllerAnimated(true, completion:nil)
    showLeader()
}


func showLeader() {
    var vc = self.view?.window?.rootViewController
    var gc = GKGameCenterViewController()
    gc.gameCenterDelegate = self
    vc?.presentViewController(gc, animated: true, completion: nil)
}



func gameCenterViewControllerDidFinish(gameCenterViewController: GKGameCenterViewController!)
{
    gameCenterViewController.dismissViewControllerAnimated(true, completion: nil)

}






override func prefersStatusBarHidden() -> Bool {
    return true
}


override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}


@IBAction func retryButton(sender: AnyObject) {
    self.dismissViewControllerAnimated(true, completion: nil)
}
}

编辑 成功了!我所要做的就是改变

var vc = self.view?.window?.rootViewController

到

var vc = self

Answer 1

您可能会看到此警告，因为您在 dismissViewControllerAnimated 完成动画之前显示排行榜。您应该将 showLeader() 放在 dismissViewControllerAnimated 的完成参数中。