anchor.diff:  
     @override
     Widget build(BuildContext context) {
  +    switch (Theme.of(context).platform) {
  +      case TargetPlatform.android:
  +      case TargetPlatform.fuchsia:
  +        _vibrate = true;
  +        break;
  +      case TargetPlatform.iOS:
  +        _vibrate = false;
  +        break;
  +    }
       Widget picker = new Flexible(
         child: new SizedBox(
           height: _kMaxDayPickerHeight,
  
positive.code:   }
  
    void _handleDayChanged(DateTime value) {
      HapticFeedback.vibrate();
      setState(() {
        _selectedDate = value;
      });
  
negative.code: }
  
  class _DatePickerDialogState extends State<_DatePickerDialog> {
    bool _vibrate = false;
  
    @override
    void initState() {
      super.initState();
  