title: Firebase notifications not working in iOS 11
body: <p>I'm developing an app that uses Firebase push notifications. It worked well until I tried in iOS 11. Using an iphone with ios 11 the notifications don't arrive. Here's my code:</p>
  
  <pre><code>- (void)application:(UIApplication *)application 
    didReceiveRemoteNotification:(NSDictionary *)userInfo
    fetchCompletionHandler:(void (^)
    (UIBackgroundFetchResult))completionHandler {
        //Manage notification
    }
  
  - (void)userNotificationCenter:(UNUserNotificationCenter *)center
     willPresentNotification:(UNNotification *)notification
       withCompletionHandler:(void (^)(UNNotificationPresentationOptions))completionHandler{
      //Manage notification
  }
  </code></pre>
  
  <p>Neither of the methods are called.</p>
  
  <p>Thanks for the help!</p>