how to show view controller from UIPreviewAction in swift

Question

I do support 3D Touch, I did so that when using strong pulled the cell appeared controller and then the user picked it up, he was shown the action, there will be a button to show I want when the user clicks on it, the controller fully opens. How can I show this controller?

 @available(iOS 9.0, *)
override func previewActionItems() -> [UIPreviewActionItem] {
    let showAction = UIPreviewAction(title: "Show", style: .Default) { [weak self] (action: UIPreviewAction, vc: UIViewController) -> Void in
        guard let weakSelf = self else {
            return;
        }

        if let _popAction = weakSelf.popAction {
            _popAction()
        }
        self?.showViewController(vc, sender: nil)
        print("show city controller")
    }

    return [showAction]
}

Answer 1

I changed code

 @available(iOS 9.0, *)
override func previewActionItems() -> [UIPreviewActionItem] {
    let showAction = UIPreviewAction(title: "Show", style: .Default) { [weak self] (action: UIPreviewAction, vc: UIViewController) -> Void in
        guard let weakSelf = self else {
            return;
        }

        if let _popAction = weakSelf.popAction {
            _popAction()
        }
        self?.showViewController(vc, sender: nil)
        print("show city controller")
    }
    let cityController = CityController() 
    cityController.showPreviewController()
    return [showAction]
}