gistfile1.m

 FBRequest* friends_request = [FBRequest requestForMyFriends];
    [friends_request startWithCompletionHandler:^(FBRequestConnection* connection,
                                                  NSDictionary* result,
                                                  NSError* error)
        {
            NSArray* friends = [result objectForKey:@"data"];
            //...
            for (NSDictionary<FBGraphUser>* friend in friends)
            {
                [friends_name addObject:friend.name];
                [friends_id addObject:friend.objectID];
            }
            [friends_name sortUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
            [HMSeenByAll setFriendsListNameSorted:friends_name];
            //...    
        }];