title: UNNotificationAction not showing actions
body: <p>I have following code that display notification. It's work, however, it's not showing action buttons. I wonder what could be wrong?</p>
  
  <pre><code>UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];
  
  
      UNAuthorizationOptions options = UNAuthorizationOptionAlert + UNAuthorizationOptionSound;
  
      [center requestAuthorizationWithOptions:options
                            completionHandler:^(BOOL granted, NSError * _Nullable error) {
                                if (!granted) {
                                    NSLog(@"Something went wrong");
                                }
                            }];
  
      // Objective-C
      UNMutableNotificationContent *content = [UNMutableNotificationContent new];
      content.title = @"Don't forget";
      content.body = @"Buy some milk";
      content.sound = [UNNotificationSound defaultSound];
  
      // Time
      UNTimeIntervalNotificationTrigger *trigger = [UNTimeIntervalNotificationTrigger triggerWithTimeInterval:30
                                                                                                      repeats:NO];
  
      // Objective-C
      NSString *identifier = @"UYLLocalNotification";
      UNNotificationRequest *request = [UNNotificationRequest requestWithIdentifier:identifier
                                                                            content:content trigger:trigger];
  
      [center addNotificationRequest:request withCompletionHandler:^(NSError * _Nullable error) {
          if (error != nil) {
              NSLog(@"Something went wrong: %@",error);
          }
      }];
  
  
      // Actions
      UNNotificationAction *snoozeAction = [UNNotificationAction actionWithIdentifier:@"Snooze"
                                                                                title:@"Snooze" options:UNNotificationActionOptionNone];
      UNNotificationAction *deleteAction = [UNNotificationAction actionWithIdentifier:@"Delete"
                                                                                title:@"Delete" options:UNNotificationActionOptionDestructive];
  
      // Objective-C
      UNNotificationCategory *category = [UNNotificationCategory categoryWithIdentifier:@"UYLReminderCategory"
                                                                                actions:@[snoozeAction,deleteAction] intentIdentifiers:@[]
                                                                                options:UNNotificationCategoryOptionNone];
      NSSet *categories = [NSSet setWithObject:category];
  
      // Objective-C
      [center setNotificationCategories:categories];
  
      // Objective-C
      content.categoryIdentifier = @"UYLReminderCategory";
  </code></pre>