async void AttendButton_Click(object sender, EventArgs e)
        {
            var disasterAttend = new DisasterAttend
            {
                ParticipantId = App.User.Id,
                DisasterId    = _disasterId
            };
            await Service.InsertItemAsync(disasterAttend);

            ApplicationBar.Buttons.Remove(sender as ApplicationBarIconButton);
        }
 async void AttendButton_Click(object sender, EventArgs e)
 {
     var disasterAttend = new DisasterAttend
     {
         ParticipantId = App.User.Id,
         DisasterId = _disasterId
     };
     await Service.InsertItemAsync(disasterAttend);
     ApplicationBar.Buttons.Remove(sender as ApplicationBarIconButton);
 }