XF相对布局

using System;

using Xamarin.Forms;

using Xamarin.Forms.Xaml;

[assembly: XamlCompilation (XamlCompilationOptions.Compile)]

namespace App6

{

    public partial class App : Application

    {

        public App ()

        {

            InitializeComponent();

RelativeLayout rl = new RelativeLayout();

            rl.Children.Add(new BoxView { Color = Color.Blue, WidthRequest = 150, HeightRequest = 150 }, Constraint.Constant(0), Constraint.Constant(0));

            rl.Children.Add(new BoxView { Color = Color.Red, WidthRequest = 150, HeightRequest = 150 }, Constraint.RelativeToParent((Parent)=>Parent.Width-150), Constraint.Constant(0));

            rl.Children.Add(new BoxView { Color = Color.Purple, WidthRequest = 150, HeightRequest = 150 }, Constraint.Constant(0), Constraint.RelativeToParent((Parent) => Parent.Height - 150));

            rl.Children.Add(new BoxView { Color = Color.Yellow, WidthRequest = 150, HeightRequest = 150 }, Constraint.RelativeToParent((Parent) => Parent.Width - 150), Constraint.RelativeToParent((Parent) => Parent.Height - 150));

MainPage = new ContentPage { Content=rl};

        }

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

        }

    }

}