单击按钮 Xamarin.forms 将子项添加到父项

我一直在尝试在 Android 中单击按钮时将标签视图添加到堆栈布局中。 但它会抛出空指针异常。以下是我想要实现的目标。任何人都可以请建议如何在 xamarin.forms 中实现这一目标

C# 中的 Xamarin.Forms 代码

 StackLayout parent= new StackLayout ();

 Button add= new Button
        {
            HorizontalOptions=LayoutOptions.End,
            BackgroundColor=Xamarin.Forms.Color.White,
            Text="ADD",
            TextColor=Xamarin.Forms.Color.Maroon,
        };

 add.Clicked += OnButtonClicked;
 
 Label firstLabel = new Label
        {
            Text = "Label 1",
            HorizontalOptions = LayoutOptions.StartAndExpand,
            TextColor=Xamarin.Forms.Color.FromHex("#000000")
        };
 parent.Children.Add(add);
 parent.Children.Add(firstLabel );

在按钮单击中添加标签

 void OnButtonClicked(object sender, EventArgs e)
 {

   Label secondLabel = new Label
        {
            Text = "Label 1",
            HorizontalOptions = LayoutOptions.StartAndExpand,
            TextColor=Xamarin.Forms.Color.FromHex("#000000")
        };
  parent.Children.Add(secondLabel ); 
}

提前致谢

你的代码按原样工作......只需一个微小的改变 - makeparent一个类字段，因此它是从内部引用的OnButtonClicked

请确保更新解决方案包，以便拥有最新的 Xamarin.Forms。始终在解决方案级别更新包，这样就不会出现版本冲突

该版本已经过测试并可在 iOS 上运行：

public class LabelPage: ContentPage
    {
        StackLayout parent = null;

        public LabelPage ()
        {
            parent = new StackLayout ();

            Button add = new Button {
                HorizontalOptions = LayoutOptions.End,
                BackgroundColor = Xamarin.Forms.Color.White,
                Text = "ADD",
                TextColor = Xamarin.Forms.Color.Maroon,
            };

            add.Clicked += OnButtonClicked;

            Label firstLabel = new Label {
                Text = "Label 1",
                HorizontalOptions = LayoutOptions.StartAndExpand,
                TextColor = Xamarin.Forms.Color.FromHex ("#000000")
            };
            parent.Children.Add (add);
            parent.Children.Add (firstLabel); 

            Content = parent;
        }

        void OnButtonClicked (object sender, EventArgs e)
        { 
            Label secondLabel = new Label {
                Text = "Label 1",
                HorizontalOptions = LayoutOptions.StartAndExpand,
                TextColor = Xamarin.Forms.Color.FromHex ("#000000")
            };
            parent.Children.Add (secondLabel); 
            //UpdateChildrenLayout ();
        }
    }