This is in response to Xamarin Forms Question https://forums.xamarin.com/discussion/21917/best-way-to-reproduce-spotify-grid-view

SegmentTab.cs

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Xamarin.Forms;

namespace FutureState.AppCore.Pages
{
    public class SegmentTab : ContentPage
    {
        private Grid _grid;
        private ScrollView _scrollView;

        public SegmentTab(/*Stuff in here*/)
        {
            Content = BuildPage(segmentPageViewModel);
        }

        private View BuildPage(SegmentPageViewModel segment)
        {
            _scrollView = new ScrollView {BackgroundColor = Color.FromHex("#d3d6db")};

            _grid = BuildGrid(segment.SegmentMedia);

            // Build the page.
            var contentStackLayout = new StackLayout
            {
                Orientation = StackOrientation.Vertical,
                VerticalOptions = LayoutOptions.FillAndExpand,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Padding = 10,
                Children =
                {
                    _grid,
                    webView
                }
            };

            _scrollView.Content = contentStackLayout;

            return _scrollView;
        }

        private Grid BuildGrid(IList<MediaViewModel> segmentMedia)
        {
            var grid = new Grid
            {
                RowSpacing = 10,
                ColumnSpacing = 10,
                Padding = new Thickness(0, 0, 0, 4),
                ColumnDefinitions = new ColumnDefinitionCollection
                {
                    new ColumnDefinition {Width = new GridLength(2, GridUnitType.Star)},
                    new ColumnDefinition {Width = new GridLength(2, GridUnitType.Star)}
                }
            };

            BuildTiles(grid, segmentMedia);
            return grid;
        }

        private async void BuildTiles(Grid grid, IList<MediaViewModel> segmentMedia)
        {
            for (var index = 0; index < segmentMedia.Count; index++)
            {
                var column = index%2;
                var row = (int) Math.Floor(index/2f);

                var mediaItem = segmentMedia[index];
                // Awaiting this helps the grid build up rather than locking the UI
                var vimeoItem = await GetVimeoStuffAsync(mediaItem.FileLocation.ParseVimeoId());
                vimeoItem.Number = mediaItem.Number;
                vimeoItem.Name = mediaItem.Title;

                grid.Children.Add(BuildTile(vimeoItem), column, row);

                if (column%2 == 0)
                {
                    grid.RowDefinitions.Add(new RowDefinition {Height = 120});
                }
            }
        }

        public View BuildTile(VimeoViewModel mediaItem)
        {
            var imgSize = new Size(mediaItem.Pictures[0].Width, mediaItem.Pictures[0].Height);
            var videoImage = new Image
            {
                Source = new UriImageSource { 
                    Uri = new Uri(mediaItem.Pictures[0].Link), 
                    CacheValidity = new TimeSpan(10,0,0,0)}, // cache the image for 10 days
                Aspect = Aspect.AspectFill
            };
            var videoNumberBadge = new RoundedBoxView {WidthRequest = 30, HeightRequest = 30, Color = Color.FromHex(Colors.br_orange), BorderRadius = 50};
            var videoNumber = new Label {Text = mediaItem.Number.ToString(), TextColor = Color.White, Font = Font.SystemFontOfSize(25f)};
            var playIcon = new FontAwesomeLabel {FontSize = 40, Text = FontAwesome.icon_play, TextColor = Color.White};

            var innerLayout = new RelativeLayout {WidthRequest = int.MaxValue, HeightRequest = int.MaxValue, BackgroundColor = Color.Black};

            innerLayout.Children.Add(
                videoImage,
                Constraint.RelativeToParent(parent =>
                {
                    var parentSize = new Size(parent.Width, parent.Height);
                    var newImgSize = ResizeFit(imgSize, parentSize);

                    return ((double) Decimal.Subtract((decimal) parent.Width, (decimal) newImgSize.Width))/2;
                }),
                Constraint.RelativeToParent(parent =>
                {
                    var parentSize = new Size(parent.Width, parent.Height);
                    var newImgSize = ResizeFit(imgSize, parentSize);

                    return ((double) Decimal.Subtract((decimal) parent.Height, (decimal) newImgSize.Height))/2;
                }));

            innerLayout.Children.Add(playIcon,
                Constraint.RelativeToParent(parent => (parent.Width/2) - 10),
                Constraint.RelativeToParent(parent => (parent.Height/2) - 20));

            innerLayout.Children.Add(videoNumberBadge,
                Constraint.RelativeToParent(parent => parent.X - 5),
                Constraint.RelativeToParent(parent => parent.Y - 5));

            innerLayout.Children.Add(videoNumber,
                Constraint.Constant(2.5),
                Constraint.RelativeToParent(parent => parent.Y - 8));

            var tile = new ContentView
            {
                BackgroundColor = Color.White,
                Content = innerLayout,
                VerticalOptions = LayoutOptions.FillAndExpand
            };

            return tile;
        }

        private static Size ResizeFit(Size originalSize, Size maxSize)
        {
            var widthRatio = maxSize.Width/originalSize.Width;
            var heightRatio = maxSize.Height/originalSize.Height;
            var minAspectRatio = Math.Min(widthRatio, heightRatio);
            return minAspectRatio > 1 ? originalSize : new Size((int) (originalSize.Width*minAspectRatio), (int) (originalSize.Height*minAspectRatio));
        }
    }
}