如何重写ios objc类的函数?

我有这门课:

  UIViewController = interface(UIResponder)
    ['{F7A5E372-3F4A-4F25-A2F9-C91D7CB5FC09}']
    ....
    function supportedInterfaceOrientations: NSUInteger; cdecl;      
    ....  
  end;
  TUIViewController = class(TOCGenericImport<UIViewControllerClass, UIViewController>)  end;

我需要覆盖InterfaceDirections中支持的函数。在Xcode下是这样的:

class NavigationController: UIViewController { 

    override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
        return .portrait
    }

}

在东京德尔福怎么做?