A custom RootElement subclass to detect when the TableView has scrolled past "maxRows", and so should load more rows

CustomRootElement.cs

using System;
using MonoTouch.Dialog;
using MonoTouch.UIKit;
using MonoTouch.Foundation;

namespace MTDialogViewControllerTest
{
	public class CustomRootElement : RootElement
	{
		public CustomRootElement (string caption, Group group) : base (caption, group)
		{
		}

		protected override UIViewController MakeViewController ()
		{
			return new CustomDialogViewController (this, true) {
				Autorotate = true
			};
		}
	}

	public class CustomDialogViewController : DialogViewController
	{
		public CustomDialogViewController (RootElement root, bool pushing): base (root, pushing)
		{
		}

		public override Source CreateSizingSource (bool unevenRows)
		{
			if (unevenRows)
				throw new NotImplementedException ("You need to create a new SourceSizing subclass, this sample does not have it");

			return new CustomSource (this);
		}

		public class CustomSource : DialogViewController.Source
		{
			public CustomSource (DialogViewController container) : base (container)
			{
			}

			public override void WillDisplay (UITableView tableView, UITableViewCell cell, NSIndexPath indexPath)
			{
				base.WillDisplay (tableView, cell, indexPath);

				if (indexPath.Row > maxRows - 20) {
					loadMoreRows ();
				}
			}
		}
	}
}