ShowDialog from an asynchronus function called in initState Flutter - flutter

Question

I am writing a code to check if the user have the correct version of my app installed otherwise redirect him on the Playstore to update the app.
I am using firebase_remote_config to store a variable to keep tract of the minimum version I want the users to use.
Package_info to get information about users app.
url_launcher to redirect to playstore from the app
My problem is that my method to check the version is asynchronous and it needs to show the dialog to the user before entering the first screen of the app.
I execute it in initState. But the build method builds the first screen before the end of my asynchronous function and my ShowDialog did not render.
How can I firstly show the result of my asynchronous function before the first build?
here is my code after some updates but not showing the Dialog before Navigating to another screen
class Splashscreen extends StatefulWidget {
#override
_SplashscreenState createState() => _SplashscreenState();
}
class _SplashscreenState extends State<Splashscreen> {
#override
void initState() {
super.initState();
SchedulerBinding.instance.addPostFrameCallback((_) {
versionCheck(context);
});
}
Future versionCheck(context) async {
//Get Current installed version of app
final PackageInfo info = await PackageInfo.fromPlatform();
double currentVersion =
double.parse(info.version.trim().replaceAll(".", ""));
//Get Latest version info from firebase config
final RemoteConfig remoteConfig = await RemoteConfig.instance;
try {
// Using default duration to force fetching from remote server.
await remoteConfig.fetch(expiration: const Duration(seconds: 10));
await remoteConfig.activateFetched();
remoteConfig.getString('force_update_current_version');
double nVersion = double.parse(remoteConfig
.getString('force_update_current_version')
.trim()
.replaceAll(".", ""));
if(nVersion > currentVersion){
showDialog(
context: context,
builder: (_) => new AlertDialog(
title: new Text("You are not up to date"),
content: new Text("To use the application, you must update it"),
actions: <Widget>[
FlatButton(
child: Text('Go To Store'),
onPressed: () {
_launchURL(PLAY_STORE_URL);
},
)
],
)
);
}
} on FetchThrottledException catch (exception) {
print(exception);
} catch (exception) {
print(
'Unable to fetch remote config. Cached or default values will be used');
}
}
_launchURL(String url) async {
if (await canLaunch(url)) {
await launch(url);
} else {
throw 'Could not launch $url';
}
}
#override
Widget build(BuildContext context) {
return ScopedModelDescendant<UserModel>(builder: (context, child, model) {
return new SplashScreen(
seconds: 4,
navigateAfterSeconds:
model.isSignedIn ? HomePage() : SuggestLoginPage(),
image: new Image.asset('assets/images/logo.png', fit: BoxFit.cover,),
backgroundColor: Color(0xff131921),
styleTextUnderTheLoader: new TextStyle( ),
photoSize: 100.0,
loaderColor: Colors.white
);
});
}
}

Answer 1

Create a splash screen when the app running first time show your logo or a loader.
class SplashScreen extends StatefulWidget {
#override
_SplashScreenState createState() => _SplashScreenState();
}
cclass _SplashScreenState extends State<SplashScreen> {
#override
void initState() {
super.initState();
SchedulerBinding.instance.addPostFrameCallback((_) {
checkVersion();
});
}
Future checkVersion({String payload}) async {
var upToDate = false;
if (upToDate)
print('Navigate to Home');
else
return showDialog(
context: context,
builder: (_) => new AlertDialog(
title: new Text("You are not up to date"),
content: new Text("To use the application, you must update it"),
actions: <Widget>[
FlatButton(
child: Text('Go To Store'),
onPressed: () {
//navigate to store
},
)
],
)
);
}
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
"Stackowerflow",
style: TextStyle(
fontFamily: "Josefin",
fontSize: 55,
fontWeight: FontWeight.bold,
color: Colors.grey,
),
),
Image.asset('assets/images/splash.gif',width: 500,
height: 500,),
],
),
),
);
}
Don't forget to run this splash screen into main.dart
Now you can add your function into checkVersion and if up to date then return home or whatever u want to redirect but if it is not then redirect to the store