我的 segue 不工作

my segue is not working

我有一个按钮,如果用户点击它它必须显示另一个 vc 并且它工作正常直到我添加 UIAlertController 它从用户那里获取数据并且在用户点击完成后 alertaction 没有任何反应 这是我的代码:

    @IBAction func DfsClicked(_ sender: AnyObject) {
    let alertController = UIAlertController(title: "DFS?", message: "Please input DFS depth:", preferredStyle: .alert)
    let confirmAction = UIAlertAction(title: "Confirm", style: .default) { (_) in
        if let field = alertController.textFields?[0] {
            // store your data
            self.depth = Int(field.text!)!
            print(self.depth)
            Puzzle.AnswerNode = dfs(inputdepth: self.depth,SortedPuzzle:self.SortedPuzzle)
        } else {
            // user did not fill field
        }
    }
    let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { (_) in }
    alertController.addTextField { (textField) in
        textField.placeholder = "Default is 2"
        textField.keyboardType = UIKeyboardType.numberPad
    }
    alertController.addAction(confirmAction)
    alertController.addAction(cancelAction)
    self.present(alertController, animated: true)
}

使用此方法在确认操作块内执行 segue

self.performSegue(withIdentifier: <Identifier>, sender: <Any?>)