UIView上での左右のスワイプを検出する

UIViewを継承して以下のコードを貼り付ける。

float horizontalTolerance = 10f;

public float HorizontalTolerance {
	get { return horizontalTolerance; }
	set { horizontalTolerance = value; }
}

float verticalTolerance = 6f;

public float VerticalTolerance {
	get { return verticalTolerance; }
	set { verticalTolerance = value; }
}

private UISwipeGestureRecognizerDirection swipeType = UISwipeGestureRecognizerDirection.Down;
private PointF startPoint = new PointF (0, 0);
private long startTicks = 0;

private PointF GetCurrentPoint (NSSet touches)
{
	return (touches.AnyObject as UITouch).LocationInView (this);
}

public override void TouchesBegan (NSSet touches, UIEvent evt)
{
	base.TouchesBegan (touches, evt);
	startPoint = GetCurrentPoint (touches);
	swipeType = UISwipeGestureRecognizerDirection.Down;
	startTicks = DateTime.Now.Ticks;
}

public override void TouchesMoved (NSSet touches, UIEvent evt)
{
	base.TouchesMoved (touches, evt);
	PointF currentPoint = GetCurrentPoint (touches);
	if (Math.Abs (startPoint.X - currentPoint.X) >= HorizontalTolerance && Math.Abs (startPoint.Y - currentPoint.Y) <= VerticalTolerance) {
		if (startPoint.X < currentPoint.X) {
			swipeType = UISwipeGestureRecognizerDirection.Left;
		} else {
			swipeType = UISwipeGestureRecognizerDirection.Right;
		}
	}
}

public override void TouchesEnded (NSSet touches, UIEvent evt)
{
	base.TouchesEnded (touches, evt);
	PointF currentPoint = GetCurrentPoint (touches);
	if (swipeType == UISwipeGestureRecognizerDirection.Down)
		return;
	long ticks = DateTime.Now.Ticks - startTicks;
	float diff = Math.Abs (startPoint.X - currentPoint.X);
	double speed = diff / ticks;

	// なにかの処理。
}

UIViewを継承しているclassであればどれでも使える(使い道は別として)。

追記 2011/08/01
UISwipeGestureRecognizerを使う方法があった。