Error with passing data between tableview

I want to pass data from first table view controller to second table view controller. I using this code to do it:

first view controller:

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
            
        let detailViewController = DetailViewController()
        detailViewController.index = indexPath.row + 1
        print(detailViewController.index) // get correct indexPath.row
            
        navigationItem.backBarButtonItem = UIBarButtonItem(title: "", style: .plain, target: nil, action: nil)
        self.navigationController?.pushViewController(DetailViewController(), animated: true)
    }

second view controller:

var index = Int()

override func viewDidLoad() {
        super.viewDidLoad()
        print(index) // get nil
}

Why this happens and how to fix it?

>Solution :

You’re creating two instances of DetailViewController, separately.

//This one with a valid index
let detailViewController = DetailViewController()
detailViewController.index = indexPath.row + 1

//This one without an index
self.navigationController?.pushViewController(DetailViewController(), animated: true)

You should pass the first one into .pushViewController like this:

self.navigationController?.pushViewController(detailViewController, animated: true)