how do you do the extra credit for stage 5 in the self destructing messaging app for iOS? Any ideas?

#import "inboxViewControler.h"
#import "ImageViewController.h"



@interface inboxViewControler ()

@end

@implementation inboxViewControler

- (void)viewDidLoad {
    [super viewDidLoad];

    self.moviePlayer = [[MPMoviePlayerController alloc] init];

    PFUser *currentUser = [PFUser currentUser]; //show current user in console
    if (currentUser) {
        NSLog(@"Current user: %@", currentUser.username);
    }
    else {
        [self performSegueWithIdentifier:@"showLogin" sender:self];
}





  }

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];

    PFQuery *query = [PFQuery queryWithClassName:@"Messages"];
// [query whereKey:@"recipientIds" equalTo:[[PFUser currentUser] objectId]];
    [query orderByDescending:@"createdAt"];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        if (error) {
            NSLog(@"Error: %@ %@", error, [error userInfo]);
        }
        else {
            // We found messages!
            self.messages = objects;
            [self.tableView reloadData];
            NSLog(@"Retrieved %d messages", [self.messages count]);
        }
    }];


}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // Return the number of rows in the section.


    return [self.messages count];


    return 0;
}

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    PFObject *message = [self.messages objectAtIndex:indexPath.row];
    cell.textLabel.text = [message objectForKey:@"senderName"];

    NSString *fileType = [message objectForKey:@"fileType"];
    if ([fileType isEqualToString:@"image"]) {
        cell.imageView.image = [UIImage imageNamed:@"icon_image"];
    }
    else {
        cell.imageView.image = [UIImage imageNamed:@"icon_video"];
    }

return cell;

}


-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{


    self.selectedMessage = [self.messages objectAtIndex:indexPath.row];
    NSString *fileType = [self.selectedMessage objectForKey:@"fileType"];
    if ([fileType isEqualToString:@"image"]) {
        [self performSegueWithIdentifier:@"showImage" sender:self];
    }
    else {
        // File type is video
        PFFile *videoFile = [self.selectedMessage objectForKey:@"file"];
        NSURL *fileUrl = [NSURL URLWithString:videoFile.url];
        self.moviePlayer.contentURL = fileUrl;
        [self.moviePlayer prepareToPlay];
//        [self.moviePlayer thumbnailImageAtTime:0 timeOption:MPMovieTimeOptionNearestKeyFrame];

        // Add it to the view controller so we can see it
        [self.view addSubview:self.moviePlayer.view];
        [self.moviePlayer setFullscreen:YES animated:YES];
    }

//delete it


    // Delete it!
    NSMutableArray *recipientIds = [NSMutableArray arrayWithArray:[self.selectedMessage objectForKey:@"recipientIds"]];
    NSLog(@"Recipients: %@", recipientIds);

    if ([recipientIds count] == 1) {
        // Last recipient - delete!
        [self.selectedMessage deleteInBackground];
    }
    else {
        // Remove the recipient and save
        [recipientIds removeObject:[[PFUser currentUser] objectId]];
        [self.selectedMessage setObject:recipientIds forKey:@"recipientIds"];
        [self.selectedMessage saveInBackground];
        //[self.deleteMessages delete:fileType]; - - - TRY TO DELETE FILE
        [recipientIds removeObject:[[PFUser currentUser] objectId]];
        [self.selectedMessage setObject:recipientIds forKey:@"recipientIds"];
        [self.selectedMessage saveInBackground];

    }

}





- (IBAction)logOut:(id)sender {

    [PFUser logOut];
    [self performSegueWithIdentifier:@"showLogin" sender:self];//logout of account
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"showLogin"]) {
        [segue.destinationViewController setHidesBottomBarWhenPushed:YES];
    }
    else if ([segue.identifier isEqualToString:@"showImage"]) {
        [segue.destinationViewController setHidesBottomBarWhenPushed:YES];
        ImageViewController *imageViewController = (ImageViewController *)segue.destinationViewController;
        imageViewController.message = self.selectedMessage;
    }

}
@end





            ```