How to request and check permissions in Flutter

问题

I am using a various plugin to get user data, contact, photos and camera when the user clicks Don't allow, The application goes silent. I want to show the user the ask permission dialog when the user checks the Never ask again and Don't allow and enters the application again.

Currently the app never ask to again when the user checks Don't allow

I Know Users must grant permission for an app to access personal information, including the current location, camera, calendar, contacts, mediaLibrary, microphone, sensors, speech and photos. Although people appreciate the convenience of using an app that has access to this information, they also expect to have control over their private data. For example, people like being able to automatically tag photos with their physical location or find nearby friends, but they also want the option to disable such features.

How to ask for user permission again in flutter?

回答1:

I was very troubled with this issue After applying several solutions I found this solution. So I want to share it with everyone, that's why I asked the question and I answered

On most operating systems, permissions aren't just granted to apps at install time. Rather, developers have to ask the user for permissions while the app is running.

The best way to handle permissions is by using the permission_handler plugin. This plugin provides a cross-platform (iOS, Android) API to request permissions and check their status.

We can also open the device's app settings so users can grant permission. On Android, we can show a rationale for requesting permission.

Add this to your package's pubspec.yaml file:

dependencies:
  permission_handler: ^5.0.1+1

Now in your Dart code, you can use:

import 'package:permission_handler/permission_handler.dart';

While the permissions are being requested during runtime, you'll still need to tell the OS which permissions your app might potentially use. That requires adding permission configuration to Android- and iOS-specific files.

iOS
- Add permission to your Info.plist file. Here's an example Info.plist with a complete list of all possible permissions.
Android
1. Add the following to your "gradle.properties" file:
```
android.useAndroidX=true
android.enableJetifier=true
```
2. Make sure you set the compileSdkVersion in your "android/app/build.gradle" file to 28:
```
android {
  compileSdkVersion 28
  ...
}
```
3. Make sure you replace all the android. dependencies to their AndroidX counterparts (a full list can be found here: https://developer.android.com/jetpack/androidx/migrate)
Add permissions to your AndroidManifest.xml file. There's a debug, main and profile version which are chosen depending on how you start your app. In general, it's sufficient to add permission only to the main version. Here's an example AndroidManifest.xml with a complete list of all possible permissions.

There are a number of Permissions. You can get a Permission's status, which is either undetermined, granted, denied, restricted or permanentlyDenied.

var status = await Permission.camera.status;
if (status.isUndetermined) {
  // We didn't ask for permission yet.
}

// You can can also directly ask the permission about its status.
if (await Permission.location.isRestricted) {
   // The OS restricts access, for example because of parental controls.
}

Call request() on a Permission to request it. If it has already been granted before, nothing happens. request() returns the new status of the Permission.

if (await Permission.contacts.request().isGranted) {
  // Either the permission was already granted before or the user just granted it.
}

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

On Android, you can show a rationale for using a permission:

bool isShown = await Permission.contacts.shouldShowRequestRationale;

Full Example

Container(
  child: Wrap(
    children: <Widget>[
      ListTile(
          leading: Icon(Icons.camera_enhance),
          title: Text(getTranslated(context, "Camera")),
          onTap: () async {
            var status = await Permission.camera.status;
            if (status.isGranted) {
              final pickedFile =
                  await _picker.getImage(source: ImageSource.camera);
              final File file = File(pickedFile.path);
              imageSelected(file);
            } else if (status.isUndetermined) {
              final pickedFile =
                  await _picker.getImage(source: ImageSource.camera);
              final File file = File(pickedFile.path);
              imageSelected(file);
            } else {
              showDialog(
                  context: context,
                  builder: (BuildContext context) => CupertinoAlertDialog(
                        title: Text('Camera Permission'),
                        content: Text(
                            'This app needs camera access to take pictures for upload user profile photo'),
                        actions: <Widget>[
                          CupertinoDialogAction(
                            child: Text('Deny'),
                            onPressed: () => Navigator.of(context).pop(),
                          ),
                          CupertinoDialogAction(
                            child: Text('Settings'),
                            onPressed: () => openAppSettings(),
                          ),
                        ],
                      ));
            }
          }),
    ],
  ),
)

来源：https://stackoverflow.com/questions/64646085/how-to-request-and-check-permissions-in-flutter

标签

Flutter

dart

permissions

android-permissions

ios-permissions