Using UIGestureRecognizer in Xamarin.iOS ref: http://qiita.com/amay077/items/a6754176f2abe339adce

GesturesSampleViewController.cs

using System;
using System.Drawing;
using MonoTouch.Foundation;
using MonoTouch.UIKit;
using System.Diagnostics;

namespace GesturesSample
{
    public partial class GesturesSampleViewController : UIViewController
    {
        public GesturesSampleViewController() : base ("GesturesSampleViewController", null)
        {
        }

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

            // Tap gesture
            this.View.AddGestureRecognizer(new UITapGestureRecognizer(tap => 
            {
                Debug.WriteLine("Double Tap.");
            }) 
            { 
                NumberOfTapsRequired = 2 // Double tap 
            });

            // Drag(Pan) gesture
            this.View.AddGestureRecognizer(new UIPanGestureRecognizer(pan => 
            {
                var p = pan.TranslationInView(this.View);
                var v = pan.VelocityInView(this.View);
                Debug.WriteLine("Pan. transration:{0}, velocity:{1}", p, v);
            }));

            // Pinch gesture
            this.View.AddGestureRecognizer(new UIPinchGestureRecognizer(pin => 
            {
                var scale = pin.Scale;
                var v = pin.Velocity;
                Debug.WriteLine("Pinch. scale:{0}, velocity:{1}", scale, v);
            }));

            // Swipe gesture
            this.View.AddGestureRecognizer(new UISwipeGestureRecognizer(sw => 
            {
                Debug.WriteLine("Swipe.");
            }));

            // Rotate gesture
            this.View.AddGestureRecognizer(new UIRotationGestureRecognizer(ro => 
            {
                var rotation = ro.Rotation;
                var v = ro.Velocity;
                Debug.WriteLine("Rotate. rotation:{0}, velocity:{1}", rotation, v);
            }));

            // Long press gesture
            this.View.AddGestureRecognizer(new UILongPressGestureRecognizer(lp => 
            {
                Debug.WriteLine("Long press.");
            }));

        }
    }
}