ViewController没有初始化程序吗？

我试图从模型类访问一个枚举，以编写一个切换案例来执行segue。这是我的代码：

class LandingViewController: UIViewController {

// MARK: Private Structs.

private struct SegueIdentifier {
    static let forcedUpdate = "forcedUpdate"
    static let optionalUpdate = "optionalUpdate"
}


// MARK: Private variables.

private let updateType: StartupManager.UpdateType

// MARK: LifeCycle Methods.

override func viewDidLoad() {
    super.viewDidLoad()
    StartupManager.setupForLanding()

    var segueIdentifier: String
    switch updateType {
    case .ForcedUpdate: segueIdentifier = SegueIdentifier.forcedUpdate
    case .OptionalUpdate: segueIdentifier = SegueIdentifier.optionalUpdate
    }
    performSegueWithIdentifier(segueIdentifier, sender: nil)
}

将setupForLanding()被用于检查startUpManager模型类，看看哪个枚举被触发。

class StartupManager: NSObject {

enum UpdateType {
    case OptionalUpdate
    case ForcedUpdate
}
// code to perform a check
if isForceUpdate {
   completion(.ForcedUpdate)
} else {
   completion(.OptionalUpdate)
}

但是我不断收到错误消息LandingViewController has no initialisers。如何在启动管理器中签入哪种情况，然后在landingViewController中执行segue？