如何在wpf中找到由for循环创建的画布

Question

我有功能：

private string[] Letters = new string[11] {"", "A", "B", "C", "D", "E","F", "G","H", "I", "J"};

private void GenerateGameMap()
    {
        int LocA = 5;
        int LocB = 5;
        for(int i = 1; i < 12; i++)
        {
            for(int i2 = 1; i2 < 12; i2++)
            {
                Canvas canvas = new Canvas();
                canvas.Width = 26;
                canvas.Height = 26;
                canvas.Margin = new Thickness(LocA + 1, LocB + 1, 0, 0);
                Border border = new Border();
                border.BorderThickness = new Thickness(2);
                if (i == 1 || i2 == 1)
                {
                    Label label = new Label();
                    label.FontFamily = new FontFamily("Arial");
                    label.FontSize = 20;
                    label.Foreground = Brushes.White;
                    label.Margin = new Thickness(-1, -2, 0, 0);
                    label.VerticalContentAlignment = System.Windows.VerticalAlignment.Center;
                    label.HorizontalContentAlignment = System.Windows.HorizontalAlignment.Center;
                    if(i == 1)
                    {
                        if(i2 > 1)
                        {
                            label.Content = Litery[i2 - 1];
                        }
                    }else
                    {
                        if(i2==1)
                        {
                            label.Content = (i - 1).ToString();
                        }
                    }
                    border.BorderBrush = Brushes.Gold;
                    canvas.Background = Brushes.Black;
                    canvas.Children.Add(label);
                }else
                {
                    border.BorderBrush = Brushes.CadetBlue;
                    canvas.Background = Brushes.BurlyWood;
                }
                if(i > 1 && i2 > 1 )
                {
                    canvas.Name = Letters[i2 - 1] + (i - 1).ToString();
                    canvas.MouseLeftButtonUp +=canvas_MouseLeftButtonUp;
                }
                border.Width = 28;
                border.Height = 28;
                border.Margin = new Thickness(LocA, LocB, 0, 0);
                LocA+=30;
                MainGameCanvas.Children.Add(canvas);
                MainGameCanvas.Children.Add(border);
                if(i2 == 11)
                {
                    LocA = 5;
                }
            }
            LocB += 30;
        }
    }

这个功能一切都很好。但是当我想找到帆布时：

private void Button_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
    {
        string canvasName = Text1.Text + Text2.Text;
        var GameObject = MainGameCanvas.FindName(canvasName);
        Canvas SelectedGameobject = GameObject as Canvas;
        SelectedGameobject.Background = Brushes.YellowGreen;
    }

我收到错误'对象引用没有在对象的实例上设置'在行“SelectedGameobject.Background = Brushes.YellowGreen;”中。还有其他方法可以找到这种控制吗？正如我所说，我确信函数GenerateGameMap（）正在进行核心工作。