QSTodoListViewController.cs

// This file has been autogenerated from parsing an Objective-C header file added in Xcode.
using System;
using MonoTouch.UIKit;
using MonoTouch.Foundation;
using System.Threading.Tasks;

namespace amay077_baas_test
{
	public partial class QSTodoListViewController : UITableViewController
	{

		QSTodoService todoService;
		bool useRefreshControl = false;

		public QSTodoListViewController (IntPtr handle) : base (handle)
		{
		}

		public override void ViewDidLoad ()
		{
			base.ViewDidLoad ();

			todoService = QSTodoService.DefaultService;

			todoService.BusyUpdate += (bool busy) => {
				if (busy)
					activityIndicator.StartAnimating ();
				else 
					activityIndicator.StopAnimating ();
			};

			AddRefreshControl ();
		}

        public override async void ViewDidAppear(bool animated)
        {
            base.ViewDidAppear(animated);

            if (QSTodoService.DefaultService.User == null)
            {
                await QSTodoService.DefaultService.LoginAndGetData(this);
            }

            if (QSTodoService.DefaultService.User == null)
            {
                // TODO:: show error
                return;
            } 

            RefreshAsync();
        }

		async Task RefreshAsync ()
		{
			// only activate the refresh control if the feature is available
			if (useRefreshControl)
				RefreshControl.BeginRefreshing ();

			await todoService.RefreshDataAsync ();

			if (useRefreshControl) 
				RefreshControl.EndRefreshing ();

			TableView.ReloadData ();
		}

		#region UITableView methods
		public override int RowsInSection (UITableView tableview, int section)
		{
			if (todoService == null || todoService.Items == null)
				return 0;

			return todoService.Items.Count;
		}

		public override int NumberOfSections (UITableView tableView)
		{
			return 1;
		}

		public override UITableViewCell GetCell (UITableView tableView, NSIndexPath indexPath)
		{
			const string CellIdentifier = @"Cell";
			var cell = tableView.DequeueReusableCell (CellIdentifier);
			if (cell == null) {
				cell = new UITableViewCell (UITableViewCellStyle.Default, CellIdentifier);
			}

			// Set the label on the cell and make sure the label color is black (in case this cell
			// has been reused and was previously greyed out
			var label = (UILabel)cell.ViewWithTag (1);
			label.TextColor = UIColor.Black;
			label.Text = todoService.Items [indexPath.Row].Text;

			return cell;
		}

		public override string TitleForDeleteConfirmation (UITableView tableView, NSIndexPath indexPath)
		{
			// Customize the Delete button to say "complete"
			return @"complete";
		}

		public override UITableViewCellEditingStyle EditingStyleForRow (UITableView tableView, NSIndexPath indexPath)
		{
			// Find the item that is about to be edited
			var item = todoService.Items [indexPath.Row];

			// If the item is complete, then this is just pending upload. Editing is not allowed
			if (item.Complete)
				return UITableViewCellEditingStyle.None;

			// Otherwise, allow the delete button to appear
			return UITableViewCellEditingStyle.Delete;
		}

		async public override void CommitEditingStyle (UITableView tableView, UITableViewCellEditingStyle editingStyle, NSIndexPath indexPath)
		{
			// Find item that was commited for editing (completed)
			var item = todoService.Items [indexPath.Row];

			// Change the appearance to look greyed out until we remove the item
			var label = (UILabel)TableView.CellAt (indexPath).ViewWithTag (1);
			label.TextColor = UIColor.Gray;

			// Ask the todoService to set the item's complete value to YES, and remove the row if successful
			await todoService.CompleteItemAsync (item);

			// Remove the row from the UITableView
			tableView.DeleteRows (new [] { indexPath }, UITableViewRowAnimation.Top);
		}

		#endregion

		#region UI Actions
		async partial void OnAdd (NSObject sender)
		{
			if (string.IsNullOrWhiteSpace (itemText.Text))
				return;

			var newItem = new ToDoItem {
				Text = itemText.Text, 
				Complete = false
			};

			await todoService.InsertTodoItemAsync (newItem);

			var index = todoService.Items.FindIndex (item => item.Id == newItem.Id);

			TableView.InsertRows (new [] { NSIndexPath.FromItemSection (index, 0) },
			UITableViewRowAnimation.Top);

			itemText.Text = "";
		}

		#endregion

		#region UITextFieldDelegate methods
		[Export ("textFieldShouldReturn:")]
		public virtual bool ShouldReturn (UITextField textField)
		{
			textField.ResignFirstResponder ();
			return true;
		}
		#endregion

		#region * iOS Specific Code
		// This method will add the UIRefreshControl to the table view if
		// it is available, ie, we are running on iOS 6+
		void AddRefreshControl ()
		{
			if (UIDevice.CurrentDevice.CheckSystemVersion (6, 0)) {
				// the refresh control is available, let's add it
				RefreshControl = new UIRefreshControl ();
				RefreshControl.ValueChanged += async (sender, e) => {
					await RefreshAsync ();
				};
				useRefreshControl = true;
			}
		}
		#endregion
	}
}

QSTodoService.cs

using System;
using System.Net.Http;
using System.Threading.Tasks;
using System.Collections.Generic;
using Microsoft.WindowsAzure.MobileServices;
using MonoTouch.UIKit;

namespace amay077_baas_test
{
	public class QSTodoService : DelegatingHandler
	{
		static QSTodoService instance = new QSTodoService ();
		const string applicationURL = @"https://amay077-baas-test.azure-mobile.net/";
		const string applicationKey = @"ECQOoXDqFtFZCeEaXBaEpBbOcTqvyx28";
		MobileServiceClient client;
		IMobileServiceTable<ToDoItem> todoTable;
		int busyCount = 0;

		public event Action<bool> BusyUpdate;

        // Mobile Service logged in user
        private MobileServiceUser user; 
        public MobileServiceUser User { get { return user; } }

		QSTodoService ()
		{
			CurrentPlatform.Init ();

			// Initialize the Mobile Service client with your URL and key
			client = new MobileServiceClient (applicationURL, applicationKey, this);
		}

        private async Task Authenticate(UIViewController view)
        {
            try
            {
                user = await client.LoginAsync(view, MobileServiceAuthenticationProvider.Twitter);
            }
            catch (Exception ex)
            {
                Console.Error.WriteLine (@"ERROR - AUTHENTICATION FAILED {0}", ex.Message);
            }
        }

        private async Task CreateTable()
        {
            // Create an MSTable instance to allow us to work with the TodoItem table
            todoTable = client.GetTable<ToDoItem>();
        }

        public async Task LoginAndGetData(UIViewController view)
        {
            await Authenticate(view);
            await CreateTable();
        }

		public static QSTodoService DefaultService {
			get {
				return instance;
			}
		}

		public List<ToDoItem> Items { get; private set;}

		async public Task<List<ToDoItem>> RefreshDataAsync ()
		{
			try {
				// This code refreshes the entries in the list view by querying the TodoItems table.
				// The query excludes completed TodoItems
				Items = await todoTable
					.Where (todoItem => todoItem.Complete == false).ToListAsync ();

			} catch (MobileServiceInvalidOperationException e) {
				Console.Error.WriteLine (@"ERROR {0}", e.Message);
				return null;
			}

			return Items;
		}

		public async Task InsertTodoItemAsync (ToDoItem todoItem)
		{
			try {
				// This code inserts a new TodoItem into the database. When the operation completes
				// and Mobile Services has assigned an Id, the item is added to the CollectionView
				await todoTable.InsertAsync (todoItem);
				Items.Add (todoItem); 

			} catch (MobileServiceInvalidOperationException e) {
				Console.Error.WriteLine (@"ERROR {0}", e.Message);
			}
		}

		public async Task CompleteItemAsync (ToDoItem item)
		{
			try {
				// This code takes a freshly completed TodoItem and updates the database. When the MobileService 
				// responds, the item is removed from the list 
				item.Complete = true;
				await todoTable.UpdateAsync (item);
				Items.Remove (item);

			} catch (MobileServiceInvalidOperationException e) {
				Console.Error.WriteLine (@"ERROR {0}", e.Message);
			}
		}

		void Busy (bool busy)
		{
			// assumes always executes on UI thread
			if (busy) {
				if (busyCount++ == 0 && BusyUpdate != null)
					BusyUpdate (true);

			} else {
				if (--busyCount == 0 && BusyUpdate != null)
					BusyUpdate (false);

			}
		}

		#region implemented abstract members of HttpMessageHandler

		protected override async Task<System.Net.Http.HttpResponseMessage> SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
		{
			Busy (true);
			var response = await base.SendAsync (request, cancellationToken);

			Busy (false);
			return response;
		}

		#endregion
	}
}