flutter how to fix permission handler error - flutter

Question

I dont know how to resolve this red error part.
I copied this from internet then i got this error.
please help me to solve this.
This is my full code.
import 'package:flutter/material.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:android_intent/android_intent.dart';
import 'package:geolocator/geolocator.dart';
class AskForPermission extends StatefulWidget {
#override
_AskForPermissionState createState() => _AskForPermissionState();
}
class _AskForPermissionState extends State<AskForPermission> {
final PermissionHandler permissionHandler = PermissionHandler();
Map<PermissionGroup, PermissionStatus>? permissions;
void initState() {
super.initState();
requestLocationPermission();
_gpsService();
}
Future<bool> _requestPermission(PermissionGroup permission) async {
final PermissionHandler _permissionHandler = PermissionHandler();
var result = await _permissionHandler.requestPermissions([permission]);
if (result[permission] == PermissionStatus.granted) {
return true;
}
return false;
}
/*Checking if your App has been Given Permission*/
Future<bool> requestLocationPermission({Function? onPermissionDenied}) async {
var granted = await _requestPermission(PermissionGroup.location);
if (granted!=true) {
requestLocationPermission();
}
debugPrint('requestContactsPermission $granted');
return granted;
}
/*Show dialog if GPS not enabled and open settings location*/
Future _checkGps() async {
if (!(await Geolocator.isLocationServiceEnabled())) {
if (Theme.of(context).platform == TargetPlatform.android) {
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: Text("Can't get gurrent location"),
content:const Text('Please make sure you enable GPS and try again'),
actions: <Widget>[
FlatButton(child: Text('Ok'),
onPressed: () {
final AndroidIntent intent = AndroidIntent(
action: 'android.settings.LOCATION_SOURCE_SETTINGS');
intent.launch();
Navigator.of(context, rootNavigator: true).pop();
_gpsService();
})],
);
});
}
}
}
/*Check if gps service is enabled or not*/
Future _gpsService() async {
if (!(await Geolocator.isLocationServiceEnabled())) {
_checkGps();
return null;
} else
return true;
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Ask for permisions'),
backgroundColor: Colors.red,
),
body: Center(
child: Column(
children: <Widget>[
Text("All Permission Granted"),
],
))
);
}
}

Answer 1

I got the same problem - the code that worked with permission_handler ^8.0.0+2 didn't work anymore after I upgraded to ^8.3.0 - the code wouldn't compile, the Permission and the other classes where not "found" anymore (I use VS Code)
I fixed it by cleaning the pub cache:
flutter pub cache clean
and afterwards just get again the dependencies:
flutter pub get
PS: for upgrading to 8.3.0, I set targetSdkVersion and compileSdkVersion to 31 into build.gradle file

Answer 2

Install permission handler package from here. Then in your .dart file add import and call permission asking function somewhere. E.g. function like this asks for storage permission.
import 'package:permission_handler/permission_handler.dart';
Future<void> getStoragePermission() async {
if (await Permission.manageExternalStorage.request().isGranted) {
setState(() {});
} else if (await Permission.storage.request().isPermanentlyDenied) {
await openAppSettings();
} else if (await Permission.storage.request().isDenied) {
setState(() {});
}
}

Answer 3

Please refer to below code
https://pub.dev/packages/permission_handler/install
permission_handler: ^5.0.1+1
import 'package:permission_handler/permission_handler.dart';
import 'package:google_fonts/google_fonts.dart';
class MyApp extends StatelessWidget {
MyApp({Key key}) : super(key: key);
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primaryColor: Color(0xfff00B074),
textTheme: const TextTheme(
bodyText1: TextStyle(
fontSize: 18.0,
fontFamily: 'Barlow-Medium',
color: Color(0xff464255)),
),
),
home: PermissionHandlerScreen(),
);
}
}
class PermissionHandlerScreen extends StatefulWidget {
#override
_PermissionHandlerScreenState createState() =>
_PermissionHandlerScreenState();
}
class _PermissionHandlerScreenState extends State<PermissionHandlerScreen> {
#override
void initState() {
super.initState();
permissionServiceCall();
}
permissionServiceCall() async {
await permissionServices().then(
(value) {
if (value != null) {
if (value[Permission.storage].isGranted &&
value[Permission.camera].isGranted &&
value[Permission.microphone].isGranted) {
/* ========= New Screen Added ============= */
Navigator.pushReplacement(
context,
MaterialPageRoute(builder: (context) => SplashScreen()),
);
}
}
},
);
}
/*Permission services*/
Future<Map<Permission, PermissionStatus>> permissionServices() async {
// You can request multiple permissions at once.
Map<Permission, PermissionStatus> statuses = await [
Permission.storage,
Permission.camera,
Permission.microphone,
//add more permission to request here.
].request();
if (statuses[Permission.storage].isPermanentlyDenied) {
openAppSettings();
setState(() {});
} else {
if (statuses[Permission.storage].isDenied) {
permissionServiceCall();
}
}
if (statuses[Permission.microphone].isPermanentlyDenied) {
openAppSettings();
setState(() {});
} else {
if (statuses[Permission.microphone].isDenied) {
permissionServiceCall();
}
}
if (statuses[Permission.camera].isPermanentlyDenied) {
openAppSettings();
setState(() {});
} else {
if (statuses[Permission.camera].isDenied) {
permissionServiceCall();
}
}
/*{Permission.camera: PermissionStatus.granted, Permission.storage: PermissionStatus.granted}*/
return statuses;
}
#override
Widget build(BuildContext context) {
permissionServiceCall();
return WillPopScope(
onWillPop: () {
SystemNavigator.pop();
},
child: Scaffold(
body: Container(
child: Center(
child: InkWell(
onTap: () {
permissionServiceCall();
},
child: Text("Click here to enable Enable Permission Screen")),
),
),
),
);
}
}
class SplashScreen extends StatelessWidget {
const SplashScreen({Key key}) : super(key: key);
#override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () {
SystemNavigator.pop();
},
child: Scaffold(
body: Center(
child: Text(
"Splash Screen",
),
),
),
);
}
}

Answer 4

Add permission_handler dependency in your pubspec.yaml file.
Try the flutter pub get command. If already done, then refer to this link about the permission handler package.