TappedGestureRecognizer single = new TappedGestureRecognizer();
TappedGestureRecognizer double = new TappedGestureRecognizer();
double.NumberOfTapsRequired = 2;
single.Tapped += OnSingleTap;
double.Tapped += OnDoubleTap;

// assuming you're within a Control's context
this.GestureRecognizers.Add(single);
this.GestureRecognizers.Add(double);

protected void OnSingleTap(object sender, EventArgs e) {
}

protected void OnDoubleTap(object sender, EventArgs e) {
}