class MovieListViewController: UICollectionViewController {

  //...

  override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    guard let movieDetailVC = segue.destination as? MovieDetailViewController, let cell = sender as? UICollectionViewCell, let indexPath = collectionView.indexPath(for: cell)  else {
      fatalError("Unexpected View Controller")
     }

     let movie = movies[indexPath.item]
     movieDetailVC.movie = movie
  }

}