main.dart

import 'package:demo/profile.dart';
import 'package:demo/second.dart';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Nepal',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: FirstScreen(),
      routes: {
        //about
        //settings

        "/secondScreen": (context) => SecondScreen(),
      },
      // onUnknownRoute: ,
      onGenerateRoute: (setting) {
        // profile
        // detail screen
        // post detail
        //
        var name = setting.name;
        var splits = name.split("/");

        // /profile/21
        // ["","profile","21"];

        // /detail/31
        // ["", "detail","31"];

        switch (splits[1]) {
          case "profile":
            var profileId = splits[2];
            return MaterialPageRoute(
                builder: (context) => ProfileScreen(profileId));
            break;
          default:
        }
      },
    );
  }
}

class FirstScreen extends StatefulWidget {
  @override
  _FirstScreenState createState() => _FirstScreenState();
}

class _FirstScreenState extends State<FirstScreen> {
  int selectedMenu = 0;
  var _pageController = PageController();

  var names = [
    "Jon",
    "Emy",
    "Test",
    "Prasanna",
    "Aawaz",
    "New Name",
    "Again New Name",
    "Feri new name",
    "Arko pani naya name",
    "Jon",
    "Emy",
    "Test",
    "Prasanna",
    "Aawaz",
    "New Name",
    "Again New Name",
    "Feri new name",
    "Arko pani naya name",
    "Jon",
    "Emy",
    "Test",
    "Prasanna",
    "Aawaz",
    "New Name",
    "Again New Name",
    "Feri new name",
    "Arko pani naya name",
  ];
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("First Screen"),
        ),
        bottomNavigationBar: BottomNavigationBar(
          currentIndex: selectedMenu,
          type: BottomNavigationBarType.fixed,
          onTap: (index) {
            _pageController.animateToPage(
              index,
              duration: Duration(milliseconds: 300),
              curve: Curves.easeInOut,
            );
            setState(() {
              selectedMenu = index;
            });
          },
          items: [
            BottomNavigationBarItem(
              backgroundColor: Colors.red,
              title: Text("Menu 1"),
              icon: Icon(
                Icons.access_alarm,
              ),
            ),
            BottomNavigationBarItem(
              backgroundColor: Colors.green,
              title: Text("Menu 2"),
              icon: Icon(
                Icons.access_alarm,
              ),
            ),
            BottomNavigationBarItem(
              backgroundColor: Colors.blue,
              title: Text("Menu 3"),
              icon: Icon(Icons.access_alarm),
            ),
            BottomNavigationBarItem(
              backgroundColor: Colors.pink,
              title: Text("Menu 4"),
              icon: Icon(Icons.access_alarm),
            ),
          ],
        ),
        body: PageView.builder(
          controller: _pageController,
          itemBuilder: (context, index) {
            return Center(
              child: FlatButton(
                onPressed: () async {
                  Navigator.pushNamed(context, "/profile/22");
                },
                child: Text("Menu ${index + 1}"),
              ),
            );
          },
          itemCount: 4,
        ));
  }
}

profile.dart

import 'package:flutter/material.dart';

class ProfileScreen extends StatelessWidget {
  final String name;
  ProfileScreen(this.name);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Profile Screen"),
      ),
      body: Center(
        child: Text("THis is a profile screen $name"),
      ),
    );
  }
}

second.dart

import 'package:flutter/material.dart';

class SecondScreen extends StatefulWidget {
  @override
  _SecondScreenState createState() => _SecondScreenState();
}

class _SecondScreenState extends State<SecondScreen> {
  var name;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Second Screen"),
      ),
      body: Center(
          child: Column(
        children: <Widget>[
          TextField(
            decoration: InputDecoration(hintText: "Name"),
            onChanged: (value) {
              setState(() {
                name = value;
              });
            },
          ),
          RaisedButton(
            child: Text("Done"),
            onPressed: () {
              Navigator.pop(context, name);
            },
          )
        ],
      )),
    );
  }
}