CustomCell.cs

using Foundation;
using UIKit;
using System;
using System.Collections.Generic;
using CoreGraphics;

namespace MonoDevelopTouchCells {
	[Register]
	public class CustomCell : UITableViewCell {
		public string Title {
			get { return this.TextLabel.Text; }
			set { this.TextLabel.Text = value; }
		}

		public bool Checked { get; set; }

		public UIButton CheckButton { get; set; }

		public CustomCell (UITableViewCellStyle style, string reuseIdentifier) : base (style, reuseIdentifier)
		{
			this.Accessory = UITableViewCellAccessory.DetailDisclosureButton;

			// cell's title label
			TextLabel.BackgroundColor = this.BackgroundColor;
			TextLabel.Opaque = false;
			TextLabel.TextColor = UIColor.Black;
			TextLabel.HighlightedTextColor = UIColor.White;
			TextLabel.Font = UIFont.BoldSystemFontOfSize (18f);

			// cell's check button
			CheckButton = new UIButton () {
				Frame = CGRect.Empty,
				VerticalAlignment = UIControlContentVerticalAlignment.Center,
				HorizontalAlignment = UIControlContentHorizontalAlignment.Center,
				BackgroundColor = this.BackgroundColor,
			};

			CheckButton.TouchDown += CheckButtonTouchDown;
			ContentView.AddSubview (this.CheckButton);
		}

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

			this.TextLabel.Frame = new CGRect (
				this.ContentView.Bounds.Left + 40f,
				8f,
				this.ContentView.Bounds.Width,
				30f);

			// layout the check button image
			UIImage checkedImage = UIImage.FromFile ("images/checked.png");

			CheckButton.Frame = new CGRect (
				this.ContentView.Bounds.Left + 10f,
				12f,
				checkedImage.Size.Width,
				checkedImage.Size.Height);

			UIImage image = this.Checked ? checkedImage : UIImage.FromFile ("images/unchecked.png");
			UIImage newImage = image.StretchableImage (12, 0);

			CheckButton.SetBackgroundImage (newImage, UIControlState.Normal);
		}

		public void CheckButtonTouchDown (object sender, EventArgs e)
		{
			this.Checked = !this.Checked;
			UIImage checkImage = this.Checked ? UIImage.FromFile ("images/checked.png") : UIImage.FromFile ("images/unchecked.png");
			this.CheckButton.SetImage (checkImage, UIControlState.Normal);
		}
	}
}