Can't get past enums.

import Foundation

enum UIBarButtonStyle {
    case Done
    case Plain
    case Bordered
}

class UIBarButtonItem {

    var title: String?
    let style: UIBarButtonStyle
    var target: AnyObject?
    var action: Selector

    init(title: String?, style: UIBarButtonStyle, target: AnyObject?, action: Selector) {
        self.title = title
        self.style = style
        self.target = target
        self.action = action
    }
}

enum Button {
    case Done(title: String)
    case Edit(title: String)

    func toUIBarButtonItem() -> UIBarButtonItem {
       switch self {
        case .Done (let titleValue):
          return UIBarButtonItem(title: titleValue, style: UIBarButtonStyle.Done, target: nil, action: nil)
        case .Edit (let titleValue):
          return UIBarButtonItem(title: titleValue, style: UIBarButtonStyle.Plain, target: nil, action: nil)

       }

    }
}

let done = Button.Done(title: "Done")
let doneButton : UIBarButtonItem = Button(done)