SecondPage.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

class SecondPage extends StatelessWidget {
  final TextEditingController textController = new TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
          child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: <Widget>[
          Padding(
            padding: const EdgeInsets.all(8.0),
            child: TextField(
              autofocus: true,
              style: TextStyle(fontSize: 20.0),
              controller: textController,
            ),
          ),
          SizedBox(
            height: 8.0,
          ),
          RaisedButton(
            child: Text(
              'Submit',
              style: TextStyle(color: Colors.white),
            ),
            color: Colors.blue,
            onPressed: () {
              Navigator.pop(context, textController.text);
            },
          )
        ],
      )),
    );
  }
}