Xamarin.Forms GridView

GridView.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Input;
using Xamarin.Forms;

namespace TimeTracker.Controls
{
    public class GridView : Grid
    {
        public static readonly BindableProperty CommandParameterProperty = BindableProperty.Create<GridView, object>(p => p.CommandParameter, null);
        public static readonly BindableProperty CommandProperty = BindableProperty.Create<GridView, ICommand>(p => p.Command, null);
        private int _maxColumns = 2;
        private float _tileHeight = 100;

        public GridView()
        {
            for (var i = 0; i < MaxColumns; i++)
            {
                ColumnDefinitions.Add(new ColumnDefinition());
            }
        }

        public Type ItemTemplate { get; set; }

        public int MaxColumns
        {
            get { return _maxColumns; }
            set { _maxColumns = value; }
        }

        public float TileHeight
        {
            get { return _tileHeight; }
            set { _tileHeight = value; }
        }

        public object CommandParameter
        {
            get { return GetValue(CommandParameterProperty); }
            set { SetValue(CommandParameterProperty, value); }
        }

        public ICommand Command
        {
            get { return (ICommand) GetValue(CommandProperty); }
            set { SetValue(CommandProperty, value); }
        }

        public async Task BuildTiles<T>(IEnumerable<T> tiles)
        {
            // Wipe out the previous row definitions if they're there.
            if (RowDefinitions.Any())
            {
                RowDefinitions.Clear();
            }
            var enumerable = tiles as IList<T> ?? tiles.ToList();
            var numberOfRows = Math.Ceiling(enumerable.Count/(float) MaxColumns);
            for (var i = 0; i < numberOfRows; i++)
            {
                RowDefinitions.Add(new RowDefinition {Height = TileHeight});
            }

            for (var index = 0; index < enumerable.Count; index++)
            {
                var column = index%MaxColumns;
                var row = (int) Math.Floor(index/(float) MaxColumns);

                var tile = await BuildTile(enumerable[index]);

                Children.Add(tile, column, row);
            }
        }

        private async Task<Layout> BuildTile(object item1)
        {
            return await Task.Run(() =>
            {
                var buildTile = (Layout) Activator.CreateInstance(ItemTemplate, item1);
                var tapGestureRecognizer = new TapGestureRecognizer
                {
                    Command = Command,
                    CommandParameter = item1
                };

                buildTile.GestureRecognizers.Add(tapGestureRecognizer);
                return buildTile;
            });
        }
    }
}

Page.xaml

 <ctrl:GridView
      HorizontalOptions="FillAndExpand"
      VerticalOptions="FillAndExpand"
      x:Name="GrdView"
      RowSpacing="5"
      ColumnSpacing="5"
      MaxColumns="2"
      TileHeight="120"
      CommandParameter="{Binding}"
      Command="{Binding StartTaskCommand}" 
      IsClippedToBounds="False">
  </ctrl:GridView>

Page.xaml.cs

    public ProjectPage()
    {
        InitializeComponent();
        
        // not sure how to define this in XAML
        GrdView.ItemTemplate = typeof(TaskTileTemplate);
    }

    protected override async void OnAppearing()
    {
        base.OnAppearing();
        await GrdView.BuildTiles(taskPageViewModel.Tasks);
    }

TaskTileTemplate.xaml

<?xml version="1.0" encoding="utf-8"?>
<AbsoluteLayout xmlns="http://xamarin.com/schemas/2014/forms"
                xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                x:Class="TimeTracker.Pages.Templates.TaskTileTemplate"
                BackgroundColor="{Binding Color, Converter={StaticResource HexToColorConverter}}"
                HorizontalOptions="CenterAndExpand" 
                VerticalOptions="CenterAndExpand">

    <Label FontSize="20" Text="{Binding Name}"
           TextColor="{Binding Color, Converter={StaticResource BrightnessInversionConverter}}"
           AbsoluteLayout.LayoutBounds=".5,.5,-1,-1" 
           AbsoluteLayout.LayoutFlags="PositionProportional" />

    <ActivityIndicator IsRunning="{Binding IsBusy}" 
                       IsVisible="{Binding IsBusy}"
                       AbsoluteLayout.LayoutBounds=".5,.5,-1,-1" 
                       AbsoluteLayout.LayoutFlags="PositionProportional" />
</AbsoluteLayout>