如何在ContainerView中更改嵌入TableveIw中的变量?迅捷

class MyView:UIViewController{


         override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
            print(segue.destination)
            let distinationVC = segue.destination as? MyTableController
            distinationVC?.topConstaints.constant = 0


         }
}
class MyTableController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    @IBOutlet weak var topConstaints: NSLayoutConstraint!

}

返回

 print(segue.destination)

<myApp. MyTableController:0 x>

但在

distinationVC?.topConstaints.constant = 0

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

我做错什么了吗?

我不知道怎么修这个