enum HomeScreenLayout: Layout {
  case portrait
  case landscape

  // Define the type of view
  typealias ViewType = HomeScreenView
  var view: HomeScreenView? {
    // return from xib or create and return them here for each layout.
  }
}

protocol HomeScreenViewDelegate: class {
  func homeScreenViewDidPressSomething(_ homeScreenView: HomeScreenView)
  ...
}

class HomeScreenView: POView { // POView is a typealias of NSView and UIView for sharing view.
  weak var delegate: HomeScreenViewDelegate?
  @IBOutlet var someLabel: UILabel?

  @IBAction func somethingDidPress() {
    delegate?.homeScreenViewDidPressSomething(self)
  }

  ...
}

class HomeScreenViewModel: ViewModel, HomeScreenViewDelegate {

  // MARK: ViewModel
  // define the type of view
  typealias ViewType = HomeScerenView
  var view: HomeScrenView? { didSet{ view?.delegate = self }}

  // Make your updates for your view.
  typealias LayoutType = ExampleLayout
  func render(layout: ExampleLayout?) {
    view?.someLabel?.text = dataSource.someValue
    view?...

    if let layout = layout, case .portrait = layout {
      // Do layout specific stuff.
    }
  }

  // MARK: HomeScreenViewDelegate
  func homeScreenViewDidPressSomething(_ homeScreenView: HomeScreenView) {
    dataSource.someValue = "new value"
    render(layout: nil)	
  }

  ...
}