özek mesaj olarak yazdım ama herkesin faydalanması için buraya da ekliyorum, kabataslak yazdım detaylandırabilirsiniz;
import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}

class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;

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

class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
bool isVisible = true;

void _incrementCounter() {
setState(() {
_counter++;
if (_counter==5) {
isVisible = false;
}
});
}

@override
Widget build(BuildContext context) {
if (isVisible) {
return deneme();
} else {
return denemeGorunmez();
}
}

Widget deneme() {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times: n $_counter',
),

],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}


Widget denemeGorunmez(){
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'Tamam',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.display1,
),
],
),
),
);
}
}