How to handle the long press action on date selection in the Flutter Calendar

void longPressed(CalendarLongPressDetails calendarLongPressDetails) {
  showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title:Container(child: new Text(" Long pressed")),
          content:Container(child: new Text("Date cell " +DateFormat('dd MMM')
              .format(calendarLongPressDetails.date)
              .toString()+ " has been long pressed")),
          actions: <Widget>[
            new FlatButton(onPressed: (){
              Navigator.of(context).pop();
            }, child: new Text('close'))
          ],
        );
      });
}
 
child: SfCalendar(
  view: CalendarView.month,
  onLongPress: longPressed,
  allowedViews: <CalendarView>[
    CalendarView.day,
    CalendarView.week,
    CalendarView.workWeek,
    CalendarView.month,
    CalendarView.timelineDay,
    CalendarView.timelineWeek,
    CalendarView.timelineWorkWeek,
    CalendarView.timelineMonth,
    CalendarView.schedule
  ],
),