Dynamic Cell Heights

I do not see any difference between setting or not setting the rowHeight to automaticDimension and estimatedRowHeight to 65.
In order to test the difference in behaviors I set the fixed cell height to 40 inside size inspector and then tried building with and without these two attributes. Aside from added performance which the estimatedRowHeight is supposed to add I’m not seeing any difference with/without the rowHeight set here.

    override func viewDidLoad() {
        tableView.rowHeight = UITableView.automaticDimension
        tableView.estimatedRowHeight = 65