AppDelegate.cs

using System;
using System.Collections.Generic;
using System.Linq;
using MonoTouch.Foundation;
using MonoTouch.UIKit;
using MonoTouch.Dialog;

namespace MTDValidation
{
    // The UIApplicationDelegate for the application. This class is responsible for launching the 
	// User Interface of the application, as well as listening (and optionally responding) to 
	// application events from iOS.
	[Register ("AppDelegate")]
	public partial class AppDelegate : UIApplicationDelegate
	{
		// class-level declarations
		UIWindow window;
		//
		// This method is invoked when the application has loaded and is ready to run. In this 
		// method you should instantiate the window, load the UI into it and then make the window
		// visible.
		//
		// You have 17 seconds to return from this method, or iOS will terminate your application.
		//
		UINavigationController navigation;
		RootElement root;

		public override bool FinishedLaunching (UIApplication app, NSDictionary options)
		{
			root = new RootElement ("Validation") {
				new Section {
					new EntryElement("Company", "Enter company name", " "),
					new EntryElement("Title", "Title", " "),
				}
			};

			var dv = new DialogViewController (root);
			navigation = new UINavigationController ();
			navigation.PushViewController (dv, true);


			dv.NavigationItem.RightBarButtonItem = new UIBarButtonItem (UIBarButtonSystemItem.Save, SaveTap);

			// create a new window instance based on the screen size
			window = new UIWindow (UIScreen.MainScreen.Bounds);

			window.RootViewController = navigation;
			
			// make the window visible
			window.MakeKeyAndVisible ();
			
			return true;
		}

		void SaveTap (object sender, EventArgs e)
		{

			for (int i = 0; i < root.Count; i++) {

				var section = root [i];
				var entryElements = section.Elements.Where (p => p is EntryElement)
					.Select (r => (EntryElement)r);


				foreach (EntryElement element in  entryElements) {
					var cell = element.GetActiveCell ();
					var textLabel = cell.TextLabel;

					textLabel.TextColor = string.IsNullOrWhiteSpace (element.Value) ? UIColor.Red : UIColor.Black;

				}
			}
		}
	}
}