Pausing timer

timer.dart

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

const Color darkBlue = Color.fromARGB(255, 18, 32, 47);

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(
        scaffoldBackgroundColor: darkBlue,
      ),
      debugShowCheckedModeBanner: false,
      home: const Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

class SecondWidget extends StatefulWidget {
  const SecondWidget({Key? key}) : super(key: key);

  @override
  State<SecondWidget> createState() => _MySecondWidgetState();
}

class _MySecondWidgetState extends State<SecondWidget> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Text('Second page'),
          ElevatedButton(
              child: Text('Go Back'),
              onPressed: () async {
                Navigator.of(context).pop();
              }),
        ],
      ),
    );
  }
}

class MyWidget extends StatefulWidget {
  const MyWidget({Key? key}) : super(key: key);

  @override
  State<MyWidget> createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  Timer? timer;
  @override
  void initState() {
    super.initState();
    initTimer();
  }

  void initTimer() {
    timer = Timer.periodic(Duration(seconds: 1), (Timer t) {
      print("Running");
    });
  }

  @override
  void dispose() {
    print(
        'test \n if you are seeing this, maybe you used Navigator.pushReplacement()');
    timer?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text('First page'),
        ElevatedButton(
            child: Text('Second page'),
            onPressed: () async {
              timer?.cancel();
              await Navigator.of(context).push(
                  MaterialPageRoute(builder: (context) => SecondWidget()));
              initTimer();
            }),
      ],
    );
  }
}