How to refresh permission after getting access to it - ios

Question

I need to access users Photos, for this I ask for permission. There are possible outcomes :
Permission granted : In this condition application resumes it normal functioning.
Permission Denied : In this case application shows an alert wherein user has option to goToSettings or to just ignore it. If user selects goToSettings and provides access to photos and comes back to application then it still says that permission is not granted. Permissions are only refreshed when I restart my application.
My Question: How to refresh the application's permission settings without restarting my application. Similar problem to my question is posted here.
Edit:
My application is a navigation controller based application and I check for access in my controller's viewDidLoad. I just tried if request permissions are refreshed if I pop and push the controller again. No luck, the results where same - it still said permission denied.
Edit 2 : Code to check for permissions
func requestAccess() -> Void {
PHPhotoLibrary.requestAuthorization {
status in
switch(status) {
case .notDetermined, .denied :
// perform relavent action
break
case .authorized , .restricted :
// perform relavent action
break
}
}
}

Answer 1

iOS kills your app when you changed privacy settings. And after next tap on app's icon your app is started from scratch. application:didFinishLaunching is called and so on. So you don't need to update permissions.

Answer 2

In your AppDelegate you could have logic in applicationDidBecomeActive to re-query the permission store for your updated permissions.
In your viewDidLoad for the view you check permissions on you could observe the notification like so;
NSNotificationCenter.defaultCenter().addObserver(
self,
selector: #selector(yourClass.applicationDidBecomeActive(_:)),
name: UIApplicationDidBecomeActiveNotification,
object: nil)

Answer 3

The code below is Objective-C.
I think you can do this when user tapping a button or something:
PHAuthorizationStatus status = [PHPhotoLibrary authorizationStatus];
if (status == PHAuthorizationStatusNotDetermined) {
// ask for authorization
[PHPhotoLibrary requestAuthorization...
} else if (status == PHAuthorizationStatusAuthorized) {
// continue accessing photos
} else {
// access denied, go to settings if you want
}