using Microsoft.Azure.NotificationHubs;
using Microsoft.WindowsAzure.Messaging;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Threading.Tasks;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.Networking.PushNotifications;
using Windows.UI.Popups;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409

namespace NoteHubApp
{
   /// <summary>
   /// An empty page that can be used on its own or navigated to within a Frame.
   /// </summary>
   public sealed partial class MainPage : Page
   {
       //Connection String & Notification Hub Name
       const string nhName = "NH Name";
       const string managementConnectionString = "NH Connection String";

       NotificationHubClient hub = NotificationHubClient.CreateClientFromConnectionString(managementConnectionString, nhName);


       List<string> registrationIds = new List<string>();
       public MainPage()
       {
           this.InitializeComponent();
       }

       private void MyButton_Click(object sender, RoutedEventArgs e)
       {
           RegisterDevices();

           RefreshAllRegistration();
       }
       private async void RegisterDevices()
       {
           var channel = await PushNotificationChannelManager.CreatePushNotificationChannelForApplicationAsync();
           // create a registration description object of the correct type, e.g.
           var reg = new WindowsRegistrationDescription(channel.Uri);
           // Create
           var result = await hub.CreateRegistrationAsync(reg);
           // Displays the registration ID so you know it was successful
           if (result.RegistrationId != null)
           {
               registrationIds.Add(result.RegistrationId);

               var dialog = new MessageDialog("Registration successful: " + result.RegistrationId);
               dialog.Commands.Add(new UICommand("OK"));
               await dialog.ShowAsync();
           }
       }
       private void Refresh_Click(object sender, RoutedEventArgs e)
       {
           RefreshAllRegistration();
       }

       private async void RefreshAllRegistration()
       {
           registrationIds.Clear();

           var allRegistrations = await hub.GetAllRegistrationsAsync(100);

           showresult.Text = "Registrations Total is " + allRegistrations.Count().ToString() + "\n";

           foreach (var registration in allRegistrations)
           {
               registrationIds.Add(registration.RegistrationId);

               showresult.Text += registration.RegistrationId + "\n";
           }

           //var dialogs = new MessageDialog("Get Registrations Number " + allRegistrations.Count().ToString());
           //dialogs.Commands.Add(new UICommand("OK"));
           //await dialogs.ShowAsync();
       }

       private void Delete_Click(object sender, RoutedEventArgs e)
       {
           DeleteDevices();
       }

       private async void DeleteDevices()
       {
           if (registrationIds.Count > 0)
           {
               var rid = registrationIds[registrationIds.Count - 1];
               // Get by ID
               var r = await hub.GetRegistrationAsync<RegistrationDescription>(rid);
               try
               {
                   // delete
                   await hub.DeleteRegistrationAsync(r);
                   registrationIds.Remove(rid);
                   var dialog = new MessageDialog("Delete Registration: " + rid);
                   dialog.Commands.Add(new UICommand("OK"));
                   await dialog.ShowAsync();
               }
               catch
               {
               }

               RefreshAllRegistration();
           }
       }
   }
}

<Page
   x:Class="NoteHubApp.MainPage"
   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
   xmlns:local="using:NoteHubApp"
   xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
   xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
   mc:Ignorable="d"
   Background="{ThemeResource ApplicationPageBackgroundThemeBrush}" Height="1027" Width="1623">
   <Grid Margin="0,0,66,30">
       <Button x:Name="MyButton" Content="Register One!" Click="MyButton_Click" Height="244" Width="243" Margin="48,610,0,0" VerticalAlignment="Top" RenderTransformOrigin="2.758,-2.919" Background="#33228919"/>
       <Button x:Name="MyButton_Copy" Content="Refresh All Register!" Click="Refresh_Click" Height="809" Width="198" Margin="723,36,0,0" VerticalAlignment="Top" Background="#33D26136"/>
       <Button x:Name="MyButton_Copy1" Content="Delete Old One!" Click="Delete_Click" Height="238" Width="374" Margin="315,613,0,0" VerticalAlignment="Top" Background="#33172D5D"/>
       <TextBox x:Name="showresult" HorizontalAlignment="Left" Margin="30,28,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Height="556" Width="664" Background="#667B857A"/>
   </Grid>
</Page>