extension UIImage {
  enum Asset : String {
    case GreenApple = "Green-Apple"
    case RedApple = "Red-Apple"
    case Banana = "Banana"
    case BigPear = "Big_Pear"
    case StopButtonEnabled = "stop.button.enabled"

    var image: UIImage {
      return UIImage(named: self.rawValue)!
    }
  }

  convenience init!(asset: Asset) {
    self.init(named: asset.rawValue)
  }
}

let image1 = UIImage(asset: .Banana)   // Prefered way
let image2 = UIImage.Asset.Apple.image // Alternate way

"alert_title" = "Title of the alert";
"alert_message" = "Some alert body there";
"greetings" = "Hello, my name is %@ and I'm %d";
"apples.count" = "You have %d apples";
"bananas.owner" = "Those %d bananas belong to %@.";

enum L10n {
  /// Title of the alert
  case AlertTitle
  /// Some alert body there
  case AlertMessage
  /// Hello, my name is %@ and I'm %d
  case Greetings(String, Int)
  /// You have %d apples
  case ApplesCount(Int)
  /// Those %d bananas belong to %@.
  case BananasOwner(Int, String)
}

extension L10n : CustomStringConvertible {
  var description : String { return self.string }

  var string : String {
    /* Implementation Details */
  }
  ...
}

func tr(key: L10n) -> String {
  return key.string
}

let title = L10n.AlertTitle.string
// -> "Title of the Alert"

// Alternative syntax, shorter
let msg = tr(.AlertMessage)
// -> "Some alert body there"

// Strings with parameters
let nbApples = tr(.ApplesCount(5))
// -> "You have 5 apples"

// More parameters of various types!
let ban = tr(.BananasOwner(2, "John"))
// -> "Those 2 bananas belong to John."

protocol StoryboardSceneType {
    static var storyboardName : String { get }
}

extension StoryboardSceneType {
    static func storyboard() -> UIStoryboard {
        return UIStoryboard(name: self.storyboardName, bundle: nil)
    }

    static func initialViewController() -> UIViewController {
        return storyboard().instantiateInitialViewController()!
    }
}

extension StoryboardSceneType where Self: RawRepresentable, Self.RawValue == String {
    func viewController() -> UIViewController {
        return Self.storyboard().instantiateViewControllerWithIdentifier(self.rawValue)
    }
    static func viewController(identifier: Self) -> UIViewController {
        return identifier.viewController()
    }
}

protocol StoryboardSegueType : RawRepresentable { }

extension UIViewController {
  func performSegue<S : StoryboardSegueType where S.RawValue == String>(segue: S, sender: AnyObject? = nil) {
    performSegueWithIdentifier(segue.rawValue, sender: sender)
  }
}

struct StoryboardScene {
  enum Message : String, StoryboardSceneType {
    static let storyboardName = "Message"

    case Composer = "Composer"
    static func composerViewController() -> UIViewController {
      return Message.Composer.viewController()
    }

    case URLChooser = "URLChooser"
    static func urlChooserViewController() -> XXPickerViewController {
      return Message.URLChooser.viewController() as! XXPickerViewController
    }
  }
  enum Wizard : String, StoryboardSceneType {
    static let storyboardName = "Wizard"

    case CreateAccount = "CreateAccount"
    static func createAccountViewController() -> CreateAccViewController {
        return Wizard.CreateAccount.viewController() as! CreateAccViewController
    }

    case ValidatePassword = "Validate_Password"
    static func validatePasswordViewController() -> UIViewController {
        return Wizard.ValidatePassword.viewController()
    }
  }
}

struct StoryboardSegue {
  enum Message : String, StoryboardSegueType {
    case Back = "Back"
    case Custom = "Custom"
    case NonCustom = "NonCustom"
  }
}

// Initial VC
let initialVC = StoryboardScene.Wizard.initialViewController()
// Generic ViewController constructor, returns a UIViewController instance
let validateVC = StoryboardScene.Wizard.ValidatePassword.viewController()
// Dedicated type var that returns the right type of VC (CreateAccViewController here)
let createVC = StoryboardScene.Wizard.createAccountViewController()

override func prepareForSegue(_ segue: UIStoryboardSegue, sender sender: AnyObject?) {
  switch StoryboardSegue.Message(rawValue: segue.identifier)! {
  case .Back:
    // Prepare for your custom segue transition
  case .Custom:
    // Prepare for your custom segue transition
  case .NonCustom:
    // Prepare for your custom segue transition
  }
}

initialVC.performSegue(StoryboardSegue.Message.Back)

extension UIColor {
  /* Private Implementation details */
  ...
}

extension UIColor {
  enum Name : UInt32 {
    /// <span style="display:block;width:3em;height:2em;border:1px solid black;background:#ffffff"></span>
    /// Alpha: 80% <br/> (0xffffffcc)
    case Translucent = 0xffffffcc
    /// <span style="display:block;width:3em;height:2em;border:1px solid black;background:#339666"></span>
    /// Alpha: 100% <br/> (0x339666ff)
    case ArticleBody = 0x339666ff
    /// <span style="display:block;width:3em;height:2em;border:1px solid black;background:#ff66cc"></span>
    /// Alpha: 100% <br/> (0xff66ccff)
    case Cyan = 0xff66ccff
    /// <span style="display:block;width:3em;height:2em;border:1px solid black;background:#33fe66"></span>
    /// Alpha: 100% <br/> (0x33fe66ff)
    case ArticleTitle = 0x33fe66ff
  }

  convenience init(named name: Name) {
    self.init(rgbaValue: name.rawValue)
  }
}

UIColor(named: .ArticleTitle)
UIColor(named: .ArticleBody)
UIColor(named: .Translucent)