ios - UIViewController 类型的值在 Xcode 7 更新后没有成员 topViewController

Question

更新到 Xcode 7 后，我收到此错误“类型 UIViewController 的值没有成员 topViewController。”还有其他人遇到这个吗？ topViewController 不再是 UIViewController 的一部分了吗？

 override func viewDidLoad() {
    super.viewDidLoad()
    self.navigationItem.leftBarButtonItem = self.editButtonItem()
    let addButton = UIBarButtonItem(barButtonSystemItem: .Search,
        target: self, action: "addButtonPressed:")
    self.navigationItem.rightBarButtonItem = addButton

    if let split = self.splitViewController {
        let controllers = split.viewControllers
        self.detailViewController =
            controllers[controllers.count-1].topViewController as? ### Error heres
        DetailViewController
    }

    model = Model(delegate: self) // create the Model
    model.synchronize() // tell model to sync its data
    self.navigationController?.toolbarHidden = false;
    self.navigationItem.backBarButtonItem = UIBarButtonItem(title:"Home", style:.Plain, target:nil, action:nil)
}

Answer 1

你必须让它明确，这样它就知道你正试图从 Swift 2 中的 UINavigationController 获取 topViewController:

self.detailViewController = (controllers[controllers.count-1] as! UINavigationController).topViewController