prepareForSegue 와 viewDidLoad 호출 시점

class MainViewController: UIViewController {
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        let identifier = segue.identifier
        if identifier == "DetailView" {
            if let detailViewController = segue.destination as? DetailViewController {
                detailViewController.tableView.reloadData()
            }
        }
    }
}