这是如何运作的？ 到底是什么情况？

Question

I am learning Xamarin and I know the basics of C#. One of the first codes I encounter is

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Xamarin.Forms;
namespace Hello
{
    public class App : Application
    {
    public App()
        {
            // The root page of your application
            MainPage = new ContentPage
            {
                Content = new StackLayout
                {
                    VerticalOptions = LayoutOptions.Center,
                    Children = {
                        new Label {
                            HorizontalTextAlignment = TextAlignment.Center,
                            Text = "Welcome to Xamarin Forms!"
                        }
                    }
                }
            };
        }
        protected override void OnStart()
        {
            // Handle when your app starts
        }
        protected override void OnSleep()
        {
            // Handle when your app sleeps
        }
        protected override void OnResume()
        {
            // Handle when your app resumes
        }
    }
}

The part where I have a problem is

Children = {
    new Label {
        HorizontalTextAlignment = TextAlignment.Center,
        Text = "Welcome to Xamarin Forms!"
}

I don't understand what's happening here. What is Children ? What is it getting assigned to?

Answer 1

Children is not assigned to, but Children is initialized . It is more confusing as property `Children' is not browsable, so it does not appear in intellisense.

Children is IList<View> .

You can initialize collection like this...

List<string> list = new List<string>{
     "s1",
     "s2",
     "s3"
};

which is equivalent to

List<string> list = new List<string>();
list.Add("s1");
list.Add("s2");
list.Add("s3");

Similarly

Children = {
    new Label{
    }
}

is equivalent to

Children.Add(new Label{  });

However, there is no official document about how to initialize collection property like this, but it seems compiler converts expression cleverly. I tried to compile and it seems it did work correctly.

You can see an example here, https://dotnetfiddle.net/8jln93