Firebase Realtime IOS can't read data permission denied

This is the error in the console

Unable to get latest value for query FQuerySpec (path: /Oeuvres/13, params: { }), client offline with no active listeners and no matching disk cache entries

[Firebase/Database][I-RDB082010] Got data message: { b = { d = "Permission denied"; s = "permission_denied"; }; r = 3; }

When I run my code

var ref: DatabaseReference!

    ref = Database.database().reference()

    ref.child("Oeuvres").child(id).getData(completion:  { error, snapshot in

      guard error == nil else {
        print("\(error!.localizedDescription)")
        return;
      }
        print(snapshot.value)
    });

Here's my rules on firebase realtime database

{
  "rules": {
      ".read": true,
      ".write": "auth !== null"
  }
} 

Anyone can help me please ?