didSelectRowAt in table view

override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    // 1: try loading the "Detail" view controller and typecasting it to be DetailViewController
    if let vc = storyboard?.instantiateViewController(withIdentifier: "Detail") as? DetailViewController {
        // 2: success! Set its selectedImage property
        vc.selectedImage = pictures[indexPath.row]

        // 3: now push it onto the navigation controller
        navigationController?.pushViewController(vc, animated: true)
    }
}