How to detect app was reopened after changing settings? - permissions

Question

I am using simple permissions plugin to request contacts permissions in my flutter app.
When user presses on 'Don't ask Again' option and denies the permission, I am giving a button which opens settings using openSettings().
Now, if User enables the permissions and presses back to come on the app, how do I detect that permission has been granted?
Here is some code to give an idea-
Text(
'Permission to access Contacts was denied.\nPlease press Settings to provide permissions and continue connecting!',
),
MaterialButton(
onPressed: () {
SimplePermissions.openSettings();
},
child: Text('Settings'),
)

Answer 1

You can use WidgetsBindingObserver class. It allows you to detect the lifecycle of a widget.
Extend your current state with WidgetsBindingObserver and add these lines to your initState.
WidgetsBinding.instance.addObserver(this); //this sets WidgetsBindingObserver
requestPermission(); //this will request the permission on initial load.
Add the following lines to your state.
#override
void didChangeAppLifecycleState(AppLifecycleState state) {
checkPermission(); //this will check the status of permission when the user returns back from the settings page.
}
checkPermission() async {
bool res = await SimplePermissions.checkPermission(Permission.Camera);
if (!res) {
setState(() {
_statusMessage = "waiting for camera permission";
});
} else {
setState(() {
_statusMessage = "camera permission has been granted";
});
}
}
Check the full example code here.