These samples relate to the Working with Gestures in Xamarin.Forms doc. The code to create a gesture recognizer for tapped events is simple:
var tapGestureRecognizer =
new TapGestureRecognizer();
//tapGestureRecognizer.NumberOfTapsRequired = 2; // double-tap
tapGestureRecognizer.Tapped += OnTapGestureRecognizerTapped;
frame.GestureRecognizers.Add(tapGestureRecognizer);
Charles Petzold, Craig Dunn