cupertino_button_sample.dart

    CupertinoButton(
          padding: const EdgeInsets.only(left: 64.0, right: 64.0),
          borderRadius: BorderRadius.all(Radius.circular(25)),
          color: Color(Const.colorPrimary),
          onPressed: () {
             if (_validate()) {
               performSubmitActions();
             }
           },
          child: new Text(
            submitText,
            style: TextStyle(fontSize: 15.0, color: Colors.white),
          ),
        ))