BottomSheet value does not update using button flutter

Question

I have a Bottom Sheet which has sets of buttons. I use the buttons to change the value of pinString and a text to show the pinString. The value of the text does not update when button is clicked. How to fix this

  showNumberPad(BuildContext context) {
    showModalBottomSheet(
      context: context,
      builder: (context) {
        return StatefulBuilder(builder: (context, setState) {
          return Container(
            height: 550.0,
            child: Column(
              children: <Widget>[
                Text(
                  "$pinString",
                ),
                KeyboardNumber(
                  n: 1,
                  onPressed: () {
                     pinIndexSetup("1");
                     setState1() {
                       pinString = "New Pin";
                     }
                  },
                ),
              ],
            ),
          );
        });
      },
    );
  }

KeyboardNumber is a custom Stateful widget where I want to pass the onPressed as a parameter. Code for keyboardNumber:

class KeyboardNumber extends StatefulWidget {
  final int n;
  final onPressed;

  const KeyboardNumber({Key key, this.n, this.onPressed}) : super(key: key);

  @override
  _KeyboardNumberState createState() => _KeyboardNumberState();
}

class _KeyboardNumberState extends State<KeyboardNumber> {
  @override
  Widget build(BuildContext context) {
    return Container(
      width: 60.0,
      height: 60.0,
      decoration: BoxDecoration(
        color: teal2,
        borderRadius: BorderRadius.all(
          Radius.circular(10),
        ),
      ),
      alignment: Alignment.center,
      child: FlatButton(
        padding: EdgeInsets.all(8.0),
        onPressed: widget.onPressed,
        height: 90.0,
        child: Text(
          "${widget.n}",
          textAlign: TextAlign.center,
          style: TextStyle(
            fontSize: 16,
            color: Colors.white,
            fontWeight: FontWeight.bold,
          ),
        ),
      ),
    );
  }
}

Answer 1

you define pinString in another state and change it in bottomeSheet state, you must define it in this line :

    showModalBottomSheet(
      context: context,
      builder: (context) {
        String pinString = 'hi';
        return StatefulBuilder(builder: (BuildContext context, StateSetter setState){
          return Container(
            height: 550.0,
            child: Column(
              children: <Widget>[
                Text(
                  "$pinString",
                ),
                FlatButton(
                  child: Text("Update"),
                  onPressed: () {
                    setState(() => pinString = 'new');
                  },
                ),
              ],
            ),
          );
        });
      },
    );
  }