Pass data between view controller segue [duplicate]

Answer 1

You are mixing two different concepts. Instead of

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    UIViewController* detailViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"DetailViewController"];
    NSMutableString *object = thisArray[indexPath.row];
    detailViewController.passedData = object;
    [self.navigationController pushViewController:detailViewController animated:YES];
}

You should do something like

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    [self performSegueWithIdentifier:YOUR_SEGUE_IDENTIFIER sender:self];        
}

and then:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
 {
     if ([segue.identifier isEqualToString:YOUR_SEGUE_IDENTIFIER]) {
         NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
         AthleteDetail *destViewController = segue.destinationViewController;
         // set whatever you want here in your destination view controller
         destViewController.passedData = object;
     }
 }

And make sure that your Segue is a Push Segue.