Iam trying to add two permissions i.e. storage and camera. I have done the required setup in androidmanifest.xml file and in the main.dart called both the requests using switch. It gives the error but the app works and the permissions are also updated

import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'package:get_storage/get_storage.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:firebase_core/firebase_core.dart';

import 'package:teamup/Connectivity/network_binding.dart';
import 'package:teamup/Views/Login/sign_in.dart';
import 'package:teamup/Views/OnboardingScreen/onboarding_screen.dart';
import 'Views/OnboardingScreen/onboarding_constants.dart';

void main() async {
  await GetStorage.init();
  WidgetsFlutterBinding.ensureInitialized();
  runApp(const MyApp());
}

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

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  late Permission cameraPermission;
  late Permission storagePermission;
  PermissionStatus cameraPermissionStatus = PermissionStatus.denied;
  PermissionStatus storagePermissionStatus = PermissionStatus.denied;

  void _listenForPermission() async {
    final cameraStatus = await Permission.camera.status;
    final storageStatus = await Permission.storage.status;
    setState(() {
      cameraPermissionStatus = cameraStatus;
      storagePermissionStatus = storageStatus;
    });

    switch (cameraStatus) {
      case PermissionStatus.denied:
        requestForPermission();
        break;
      case PermissionStatus.granted:
        break;
      case PermissionStatus.restricted:
        Navigator.pop(context);
        break;
      case PermissionStatus.limited:
        Navigator.pop(context);
        break;
      case PermissionStatus.permanentlyDenied:
        Navigator.pop(context);
        break;
    }

    switch (storageStatus) {
      case PermissionStatus.denied:
        requestForPermission();
        break;
      case PermissionStatus.granted:
        break;
      case PermissionStatus.restricted:
        Navigator.pop(context);
        break;
      case PermissionStatus.limited:
        Navigator.pop(context);
        break;
      case PermissionStatus.permanentlyDenied:
        Navigator.pop(context);
        break;
    }
  }

  Future<void> requestForPermission() async {
    final cameraStatus = await Permission.camera.request();
    final storageStatus = await Permission.storage.request();
    setState(() {
      cameraPermissionStatus = cameraStatus;
      storagePermissionStatus = storageStatus;
    });
  }

  @override
  void initState() {
    super.initState();
    _listenForPermission();
    isViewed.writeIfNull('key', 0);
    print(isViewed.read('key'));
  }

  @override
  Widget build(BuildContext context) {
    return GetMaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(primarySwatch: Colors.blue, fontFamily: 'Glory'),
      initialBinding: NetworkBinding() ,
      home: isViewed.read('key') != 0
          ? const SignInPage()
          : const OnboardingPage(),
    );
  }
}

This is the message that was displayed after installation

Launching lib\main.dart on Redmi Note 4 in debug mode...
Running Gradle task 'assembleDebug'...
√  Built build\app\outputs\flutter-apk\app-debug.apk.
Installing build\app\outputs\flutter-apk\app.apk...
W/FlutterActivityAndFragmentDelegate(21677): A splash screen was provided to Flutter, but this is deprecated. See flutter.dev/go/android-splash-migration for migration steps.
Debug service listening on ws://127.0.0.1:56092/dh3Yn3XCkGg=/ws
Syncing files to device Redmi Note 4...
I/FA      (21677): Tag Manager is not found and thus will not be used
I/flutter (21677): 0
[GETX] Instance "GetMaterialController" has been created
[GETX] Instance "GetMaterialController" has been initialized
[GETX] Instance "GetXNetworkManager" has been created
[GETX] Instance "GetXNetworkManager" has been initialized
I/Timeline(21677): Timeline: Activity_launch_request time:267480997 intent:Intent { act=android.content.pm.action.REQUEST_PERMISSIONS pkg=com.google.android.packageinstaller (has extras) }
E/flutter (21677): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: PlatformException(PermissionHandler.PermissionManager, A request for permissions is already running, please wait for it to finish before doing another request (note that you can request multiple permissions at the same time)., null, null)
E/flutter (21677): #0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:607:7)
E/flutter (21677): #1      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:156:18)
E/flutter (21677): <asynchronous suspension>
E/flutter (21677): #2      MethodChannelPermissionHandler.requestPermissions (package:permission_handler_platform_interface/src/method_channel/method_channel_permission_handler.dart:71:9)
E/flutter (21677): <asynchronous suspension>
E/flutter (21677): #3      PermissionActions.request (package:permission_handler/permission_handler.dart:44:31)
E/flutter (21677): <asynchronous suspension>
E/flutter (21677): #4      _MyAppState.requestForPermission (package:teamup/main.dart:75:26)
E/flutter (21677): <asynchronous suspension>
E/flutter (21677): 
I/Timeline(21677): Timeline: Activity_launch_request time:267501469 intent:Intent { act=android.content.pm.action.REQUEST_PERMISSIONS pkg=com.google.android.packageinstaller (has extras) }

CodePudding user response：

The switch-statements in _listenForPermission will call requestForPermission twice, if both cameraStatus and storageStatus have status PermissionStatus.denied. Therefore you get the exception:

PlatformException(PermissionHandler.PermissionManager, A request for permissions is already running, please wait for it to finish before doing another request (note that you can request multiple permissions at the same time)., null, null)

The permission_handler package allows to to request multiple permission in one call like this:

// You can request multiple permissions at once.
Map<Permission, PermissionStatus> statuses = await [
  Permission.location,
  Permission.storage,
].request();
print(statuses[Permission.location]);