if internet connection is off i want to show "No internet connection" message in SnackBar.
if internet connection is on it will show UI.
This is my code:
import 'dart:io';
import 'package:flutter/material.dart';
import 'main.dart';
class InternetCheck extends StatefulWidget {
#override
_InternetState createState() => _InternetState();
}
class _InternetState extends State<InternetCheck> {
bool _isInternet = true;
final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
checkInternet() async {
try {
final response = await InternetAddress.lookup('example.com'); // google
if (response.isNotEmpty && response[0].rawAddress.isNotEmpty) {
_isInternet = true; // internet
setState(() {});
}
} on SocketException catch (_) {
_isInternet = false; // no internet
setState(() {
_showSnackBar();
});
}
return _isInternet;
}
#override
void initState() {
checkInternet();
super.initState();
}
void _showSnackBar() {
SnackBar snackBar = SnackBar(content: Text('No Connection'));
_scaffoldKey.currentState.showSnackBar(snackBar);
}
#override
Widget build(BuildContext context) {
// checkInternet();
return MaterialApp(
home: Scaffold(
key: _scaffoldKey,
body: _isInternet == true ? Text('internet') : Text('no Internet'),
),
);
}
}
using my code when app run first time with internet off it show SnackBar but when i switch internet on and again switch internet off then it will not showing snakbar.
Check out the connectivity package. It allows you to listen for network state changes :
#override
initState() {
super.initState();
subscription = Connectivity().onConnectivityChanged.listen((ConnectivityResult result) {
if(connectivityResult == ConnectivityResult.none)
_showSnackbar();
})
}
// Be sure to cancel subscription after you are done
#override
dispose() {
super.dispose();
subscription.cancel();
}
Related
I have used connectivity_plus and internet_connection_checker packages to check the internet connectivity.
The problem occured is , the app works perfectly fine as expected when the app start's with internet on state. But when the app is opened with internet off, the dialog isn't shown !!
I assume this is happening because the build method is called before the stream of internet is listened.
Code :
class _HomePageState extends State<HomePage> {
late StreamSubscription subscription;
bool isDeviceConnected = false;
bool isAlertSet = false;
#override
void initState() {
getConnectivity();
super.initState();
}
getConnectivity() {
subscription = Connectivity().onConnectivityChanged.listen(
(ConnectivityResult result) async {
isDeviceConnected = await InternetConnectionChecker().hasConnection;
if (!isDeviceConnected && isAlertSet == false) {
showDialogBox();
setState(() {
isAlertSet = true;
});
}
},
);
}
#override
void dispose() {
subscription.cancel();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
...
);
}
showDialogBox() => showDialog(/* no internet dialog */)
Extending the question: Is it assured that this works for all the pages ?
if yes, how ?
if not , how to overcome this?
First of all you need to listen for internet connectivity in your app first screen which is probably app.dart
GlobalKey<NavigatorState> navigatorKey = GlobalKey();
final noInternet = NoInternetDialog();
class TestApp extends StatefulWidget {
#override
State<TestApp> createState() => _TestAppState();
}
class _TestAppState extends State<TestApp> {
#override
void initState() {
super.initState();
checkInternetConnectivity();
}
#override
Widget build(BuildContext context) {
return MaterialApp(...);
}
Future<void> checkInternetConnectivity() async {
Connectivity().onConnectivityChanged.getInternetStatus().listen((event)
{
if (event == InternetConnectionStatus.disconnected) {
if (!noInternet.isShowing) {
noInternet.showNoInternet();
}
}
});
}
}
Make the screen stateful in which you are calling MaterialApp and in initState of that class check for your internet connection, like above
You are saying how can I show dialog when internet connection changes for that you have to create a Generic class or extension which you can on connectivity change. You have to pass context to that dialogue using NavigatorKey
class NoInternetDialog {
bool _isShowing = false;
NoInternetDialog();
void dismiss() {
navigatorKey.currentState?.pop();
}
bool get isShowing => _isShowing;
set setIsShowing(bool value) {
_isShowing = value;
}
Future showNoInternet() {
return showDialog(
context: navigatorKey.currentState!.overlay!.context,
barrierDismissible: true,
barrierColor: Colors.white.withOpacity(0),
builder: (ctx) {
setIsShowing = true;
return AlertDialog(
elevation: 0,
backgroundColor: Colors.transparent,
insetPadding: EdgeInsets.all(3.0.h),
content: Container(...),
);
},
);
}
}
Use checkConnectivity to check current status. Only changes are exposed to the stream.
final connectivityResult = await Connectivity().checkConnectivity();
i make an enum for a connectivity :
enum ConnectivityStatus{
Wifi,
Cellular,
Offline
}
then i create a service to check the Connectivity :
import 'dart:async';
import 'package:Zabatnee/activities_app/enum/connectivity_status.dart';
import 'package:connectivity/connectivity.dart';
class ConnectivityService{
StreamController<ConnectivityStatus> connectionStatusController = StreamController<ConnectivityStatus>();
ConnectivityService(){
Connectivity().onConnectivityChanged.listen((ConnectivityResult result) {
var connectionStatus = _getStatusFromResult(result);
connectionStatusController.add(connectionStatus);
});
}
ConnectivityStatus _getStatusFromResult(ConnectivityResult result) {
switch (result) {
case ConnectivityResult.mobile:
return ConnectivityStatus.Cellular;
case ConnectivityResult.wifi:
return ConnectivityStatus.Wifi;
case ConnectivityResult.none:
return ConnectivityStatus.Offline;
default:
return ConnectivityStatus.Offline;
}
}
}
and what i need is to check the connectivity status in all screen that i created. Can I do it once for all screens all, or i must check the connnectivity for each one individually.
You can check the connectivity status once & that will be implemented for all of your app.
You just have to create a wrapper class & subscribe to the Connectivity stream & apply the logic in this wrapper class.
Your whole widget will be wrapped by this widget.
MaterialApp(
..
home: ConnectivityWrapper(
childWidget: YourWidget(), // replace this with your own home widget
),
);
The wrapper widget will look something like this:
class ConnectivityWrapper extends StatefulWidget {
ConnectivityWrapper(this.childWidget);
final Widget childWidget;
#override
_ConnectivityWrapperState createState() => _ConnectivityWrapperState();
}
class _ConnectivityWrapperState extends State<ConnectivityWrapper> {
StreamSubscription<ConnectivityStatus> subscription;
#override
void initState() {
super.initState();
subscription = connectionStatusController.stream.listen((status)
{
if(status == ConnectivityStatus.Offline) {
// Your logic here (Toast message or something else)
}
},
onDone() {
// Your logic here
},
onError: () {
// Your logic here
});
}
#override
Widget build(BuildContext context) {
return widget.childWidget;
}
#override
void dispose() {
// unsubscribe to the stream
subscription.cancel();
super.dispose();
}
}
I'm new in flutter. I wanted to create an application with local biometrics I have used local auth and i need to have help with
close the application on the click of cancel button in local_auth,
close the application when maximum tries are done.
pause the background untill authentication complete
my code is
import 'dart:async';
import 'package:LogInSignIn.dart';
import 'package:flutter/material.dart';
import 'package:cashhub/homescreen.dart';
import 'package:local_auth/local_auth.dart';
import 'package:flutter/services.dart';
void main() {
setupLocator();
runApp(new MaterialApp(
debugShowCheckedModeBanner: false,
home: new SplashScreen(),
routes: <String, WidgetBuilder>{
'/HomeScreen': (BuildContext context) => new LogInSignIn(),
},
));
}
class SplashScreen extends StatefulWidget {
#override
_SplashScreenState createState() => new _SplashScreenState();
}
class _SplashScreenState extends State<SplashScreen> {
//final LocalAuthenticationService _localAuth = locator<LocalAuthenticationService>();
final LocalAuthentication auth = LocalAuthentication();
bool _canCheckBiometrics;
List<BiometricType> _availableBiometrics;
String _authorized = 'Not Authorized';
bool _isAuthenticating = false;
startTime() async {
var _duration = new Duration(seconds: 4);
return new Timer(_duration, navigationPage);
}
Future<void> _authenticate() async {
bool authenticated = false;
try {
setState(() {
_isAuthenticating = true;
_authorized = 'Authenticating';
});
authenticated = await auth.authenticateWithBiometrics(
localizedReason: 'Scan your fingerprint to authenticate',
useErrorDialogs: true,
stickyAuth: true);
setState(() {
_isAuthenticating = false;
_authorized = 'Authenticating';
});
} on PlatformException catch (e) {
print(e);
}
if (!mounted) return;
final String message = authenticated ? 'Authorized' : 'Not Authorized';
// if( message == "Not Authorized"){
// SystemNavigator.pop();
// }
setState(() {
_authorized = message;
});
}
void navigationPage() {
Navigator.of(context).pushReplacementNamed('/HomeScreen');
}
#override
void initState() {
_authenticate();
//autho();
super.initState();
startTime();
}
#override
Widget build(BuildContext context) {
return new Scaffold(
body: new Center(
child: new Image.asset('assets/splashlogo.png',
),
),
);
}
}
anyone please help me with this 3 queries..
you can close the app with cancel click like this
setState(() {
if (isAuthorized) {
_authorizedOrNot = "Authorized";
} else {
_authorizedOrNot = "Not Authorized";
exit(0);
}
});
just so you know exit(0) need to impot dart:io
Recently I am developing first ever app in Flutter and I know the basics only.
So here's the problem which I am facing currently.
I have to Navigate One of the two screens, either Register or Home page according to old/new user, So what I did is here.
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'Register.dart';
import 'HomePage.dart';
class Authenticate extends StatefulWidget {
#override
_AuthenticateState createState() => _AuthenticateState();
}
class _AuthenticateState extends State<Authenticate> {
String _userName = "";
#override
void initState() {
super.initState();
_getUserName();
}
_getUserName() async {
SharedPreferences pref = await SharedPreferences.getInstance();
setState(() {
_userName = pref.getString('userName') ?? "";
});
}
Widget build(BuildContext context) {
if (_userName == "") {
print('name : $_userName , NEW user'); // ERROR - why it's printing on console for old User ?
return Register();
} else {
return HomePage(_userName);
}
}
}
So the problem is, even if I am opening app through old user, it is printing the debug code written for new user and there's around 0.3 sec screen visibility of Register screen.
So what should I do to fix this?
The print is happening because this line of code:
SharedPreferences pref = await SharedPreferences.getInstance();
is asynchronous, which means that it might invoke in some later point in time. Because of that the build method is called first, then your _getUserName method finished, which causes a setState and invokes a build method again.
You might want to show some kind of loader screen until sharedPrefernces is initialized and then decide wheter to show Register or Home page.
Example code:
class _AuthenticateState extends State<Authenticate> {
String _userName = "";
bool _isLoading = true;
#override
void initState() {
super.initState();
_getUserName();
}
_getUserName() async {
SharedPreferences pref = await SharedPreferences.getInstance();
setState(() {
_userName = pref.getString('userName') ?? "";
_isLoading = false;
});
}
Widget build(BuildContext context) {
if (_isLoading) {
return Center(child: CupertinoActivityIndicator());
} else if (_userName == "") {
print('name : $_userName , NEW user'); // ERROR - why it's printing on console for old User ?
return Register();
} else {
return HomePage(_userName);
}
}
}
Try this:
class _AuthenticateState extends State<Authenticate> {
String _userName;
#override
void initState() {
super.initState();
_getUserName();
}
_getUserName() async {
SharedPreferences pref = await SharedPreferences.getInstance();
setState(() {
_userName = pref.getString('userName') ?? '';
});
}
Widget build(BuildContext context) {
if (_userName == null) {
return Center(child: CircularProgressIndicator());
} else if (_userName == '') {
print('name : $_userName , NEW user');
return Register();
} else {
return HomePage(_userName);
}
}
}
In this case, _userName is null initially and will only be assigned a value after the _getUserName() returns either an empty String or an old userName. When null, the widget will build a progress indicator instead. If you don't want that, just return a Container().
I want to implement internet connectivity check into my app and I used official connectivity plugin and it is working great for displaying String Value but instead of showing string value in screen I want to display different widgets for connected and disconnected.
Here What I am Using
//
Widget result;
//
body: Container(
alignment: Alignment.center,
child: result != null ?
result : Text("unknown", style :
TextStyle(fontSize: 30,fontWeight: FontWeight.bold),
),
void checkStatus(){
Connectivity().onConnectivityChanged.listen((ConnectivityResult result) {
if(
result == ConnectivityResult.mobile ||
result == ConnectivityResult.wifi){
Text("Connected", style:TextStyle(color:Colors.red));
} else {
Text("No InterNet", style:TextStyle(color:Colors.red));
}
});
}
#override
void initState() {
super.initState();
checkStatus();
}
And I am Getting 'unknown' value
try this
class Sample extends StatefulWidget {
#override
_SampleState createState() => _SampleState();
}
class _SampleState extends State<Sample> {
Widget result;
#override
void initState() {
super.initState();
checkStatus();
}
void checkStatus() async {
var connectivityResult = await (Connectivity().checkConnectivity());
if (connectivityResult == ConnectivityResult.mobile) {
result = Text("Connected to Mobile Network");
setState(() {});
} else if (connectivityResult == ConnectivityResult.wifi) {
result = Text("Connected to WiFi");
print("Connected to WiFi");
setState(() {});
} else {
result = Text("Unable to connect. Please Check Internet Connection");
setState(() {});
print("Unable to connect. Please Check Internet Connection");
}
}
#override
Widget build(BuildContext context) {
return Center(child: result);
}
}
Try this:
Use this package for checking Internet:
data_connection_checker:
And, Inside your stateful class create stream listener i.e and a boolean value.
StreamSubscription<DataConnectionStatus> listener; bool isConnected = true;
and Inside initState:
#override
void initState() {
super.initState();
listener = DataConnectionChecker().onStatusChange.listen((status) {
switch (status) {
case DataConnectionStatus.connected:
print('Data connection is available. $status');
setState(() {
isConnected = true;
});
break;
case DataConnectionStatus.disconnected:
print('You are disconnected from the internet. $status');
setState(() {
isConnected = false;
});
break;
}
});
}
Done, This will keep listening to changes in your internet status, Thus you can prompt user as you like. Cheers, Feel free to ask if confusion and if it helps upvote :D