cupertino_datepicker_sample.dart

showModalBottomSheet(
      context: context,
      builder: (context) {
         return Container(
           color: CupertinoColors.white,
           height: MediaQuery.of(context).copyWith().size.height / 3,
           child: Column(
              children: <Widget>[
                Align(
                 alignment: Alignment.topRight,
                 child: CupertinoButton(
                 onPressed: () {
                      Navigator.of(context).pop()
                 },
                 child: Text("Done"),
                 ),
                ),
                Expanded(
                  child: CupertinoDatePicker(
                  onDateTimeChanged: (DateTime picked) {                     
                   },
                  initialDateTime: initialDate,
                  mode: CupertinoDatePickerMode.date,
                  maximumDate: DateTime.now(),
                  maximumYear: DateTime.now().year,
                  minimumYear: 1900,),
                  ),
                ],
              ),
            );
          });