findname返回空值

我在为学校写一个简单的游戏。作业是用C++编写的,但老师允许我使用C++和WPF作为挑战。我已经完成了所有的游戏逻辑,表格也基本完成了,但我遇到了一堵墙。我正在使用 Label 指示轮到谁了,我想在玩家有效移动时更改。根据 Applications = Code + Markup ,我应该可以使用 FindName 方法 Window 班级。但是,它一直在回来 null . 代码如下:

public TicTacToeGame()
{
    Title = "TicTacToe";
    SizeToContent = SizeToContent.WidthAndHeight;
    ResizeMode = ResizeMode.NoResize;

    UniformGrid playingField = new UniformGrid();
    playingField.Width = 300;
    playingField.Height = 300;
    playingField.Margin = new Thickness(20);

    Label statusDisplay = new Label();
    statusDisplay.Content = "X goes first";
    statusDisplay.FontSize = 24;
    statusDisplay.Name = "StatusDisplay"; // This is the name of the control
    statusDisplay.HorizontalAlignment = HorizontalAlignment.Center;
    statusDisplay.Margin = new Thickness(20);

    StackPanel layout = new StackPanel();
    layout.Children.Add(playingField);
    layout.Children.Add(statusDisplay);

    Content = layout;

    for (int i = 0; i < 9; i++)
    {
        Button currentButton = new Button();
        currentButton.Name = "Space" + i.ToString();
        currentButton.FontSize = 32;
        currentButton.Click += OnPlayLocationClick;

        playingField.Children.Add(currentButton);
    }

    game = new TicTacToe.GameCore();
}

void OnPlayLocationClick(object sender, RoutedEventArgs args)
{
    Button clickedButton = args.Source as Button;

    int iButtonNumber = Int32.Parse(clickedButton.Name.Substring(5,1));
    int iXPosition = iButtonNumber % 3,
        iYPosition = iButtonNumber / 3;

    if (game.MoveIsValid(iXPosition, iYPosition) && 
        game.Status() == TicTacToe.GameCore.GameStatus.StillGoing)
    {
        clickedButton.Content = 
            game.getCurrentPlayer() == TicTacToe.GameCore.Player.X ? "X" : "O";
        game.MakeMoveAndChangeTurns(iXPosition, iYPosition);

        // And this is where I'm getting it so I can use it.
        Label statusDisplay = FindName("StatusDisplay") as Label;
        statusDisplay.Content = "It is " +
            (game.getCurrentPlayer() == TicTacToe.GameCore.Player.X ? "X" : "O") +
            "'s turn";
    }
}

怎么回事?我在两个地方都用同一个名字,但是 发现名 找不到。我试过使用snoop查看层次结构,但是表单没有显示在要选择的应用程序列表中。我在StackOverflow上搜索发现 should be able to use VisualTreeHelper class ,但我不知道怎么用。

有什么想法吗?