DataGridView.IsPullToRefreshEnabled Property

using System;
using Xamarin.Forms;
using System.Collections.Generic;
using System.Collections.ObjectModel;

namespace DataGridView_PullToRefresh.Models {
    public class Product {
        string name;
        string resourceName;

        public string Name {
            get { return name; }
            set {
                name = value;
                if (Photo == null) { 
                    resourceName = "DataGridView_PullToRefresh.Images." + value + ".png";
                    if (!String.IsNullOrEmpty(resourceName))
                        Photo = ImageSource.FromResource (resourceName);
                }
            }
        }
        public Product(string name) {
            this.Name = name;
        }
        public ImageSource Photo { get; set; }
        public string Description { get; set; }
    }

    public class ProductData {
        readonly List<Product> products;
        public ObservableCollection<Product> Products { get; set; }

        public ProductData() : base() {
            this.products = new List<Product>();

            GenerateAllProducts();

            int index = new Random().Next (0, 5);
            Products = GenerateAvailableProducts (index);
        }
        ObservableCollection<Product> GenerateAvailableProducts(int number) {
            ObservableCollection<Product> availableProducts = new ObservableCollection<Product>();
            for (int i = 0; i < 4; i++)
                availableProducts.Add(products[number+i]);
            return availableProducts;
        }

        public void RefreshProducts() {
            int index = new Random().Next(0, 5);
            Products = GenerateAvailableProducts(index);
        }

        void GenerateAllProducts() {
            products.Add(new Product("Beverages") {Description = "Soft drinks, coffees, teas, beers, and ales"});
            products.Add(new Product("Condiments"){Description = "Sweet and savory sauces, relishes, spreads, and seasonings"});
            products.Add(new Product("Confections"){Description = "Desserts, candies, and sweet breads"});
            products.Add(new Product("DairyProducts"){Description = "Cheeses"});
            products.Add(new Product("Grains"){Description = "Breads, crackers, pasta, and cereal"});
            products.Add(new Product("MeatPoultry"){Description = "Prepared meats"});
            products.Add(new Product("Produce"){Description = "Dried fruit and bean curd"});
            products.Add(new Product("Seafood"){Description = "Seaweed and fish"});
        }
    }
}

using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Windows.Input;
using Xamarin.Forms;
using DataGridView_PullToRefresh.Models;

namespace DataGridView_PullToRefresh.ViewModels {
    public class ViewModel : INotifyPropertyChanged {
        ProductData data;

        bool isRefreshing = false;
        public bool IsRefreshing {
            get { return isRefreshing; }
            set {
                if (isRefreshing != value) {
                    isRefreshing = value;
                    OnPropertyChanged("IsRefreshing");
                }
            }
        }

        ObservableCollection<Product> products;
        public ObservableCollection<Product> Products {
            get { return products; }
            set {
                if (products != value) {
                    products = value;
                    OnPropertyChanged("Products");
                }
            }
        }

        ICommand pullToRefreshCommand = null;
        public ICommand PullToRefreshCommand {
            get { return pullToRefreshCommand; }
            set {
                if (pullToRefreshCommand != value) {
                    pullToRefreshCommand = value;
                    OnPropertyChanged("PullToRefreshCommand");
                }
            }
        }

        public ViewModel() {
            this.data = new ProductData();
            Products = data.Products;
            PullToRefreshCommand = new Command(ExecutePullToRefreshCommand);
        }

        void ExecutePullToRefreshCommand() {
            Task.Factory.StartNew(() => {
                Thread.Sleep(3000);
                Device.BeginInvokeOnMainThread(() => {
                    data.RefreshProducts();
                    Products = data.Products;
                    IsRefreshing = false;
                });
            });
        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected void OnPropertyChanged(string name) {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(name));
        }
    }
}

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:dxg="http://schemas.devexpress.com/xamarin/2014/forms/datagrid"
             xmlns:vm="clr-namespace:DataGridView_PullToRefresh.ViewModels"
             x:Class="DataGridView_PullToRefresh.MainPage">
    <ContentPage.BindingContext>
        <vm:ViewModel/>
    </ContentPage.BindingContext>
    <dxg:DataGridView ItemsSource="{Binding Products}" IsReadOnly="True"
                      IsPullToRefreshEnabled="true" 
                      PullToRefreshCommand="{Binding PullToRefreshCommand}" 
                      IsRefreshing="{Binding IsRefreshing, Mode=TwoWay}">
        <dxg:DataGridView.Columns>
            <dxg:ImageColumn FieldName="Photo" Width="170" 
                             VerticalContentAlignment="Center" />
            <dxg:TemplateColumn FieldName="Name"  Caption="Product Category">
                <dxg:TemplateColumn.DisplayTemplate>
                    <DataTemplate>
                        <Grid BindingContext="{Binding Source}" VerticalOptions="Center" Padding="10,0,0,0">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto" />
                                <RowDefinition Height="Auto" />
                            </Grid.RowDefinitions>
                            <Label Text="{Binding Item.Name}" Font="Bold, 28"/>
                            <Label Text="{Binding Item.Description}" Grid.Row="1" Font="Medium"/>
                        </Grid>
                    </DataTemplate>
                </dxg:TemplateColumn.DisplayTemplate>
            </dxg:TemplateColumn>
        </dxg:DataGridView.Columns>
    </dxg:DataGridView>
</ContentPage>