import Localization

class SomeSettingsClass {
  func changeLanguage() {
      Localization.preferredLanguage = LocalizableLanguage.french.code // == "fr"
  }
}

import Localization

class SomeViewController: UIViewController {
  var someLabel: UILabel = UILabel()

  override func viewDidLoad() {
    super.viewDidLoad()
    // ...

    Localization.startObserve(with: self, selector: #selector(localizationDidChangeWithPreferredLanguage))
    }

  deinit {
    Localization.stopObserve(with: self)
  }

  func localizationDidChangeWithPreferredLanguage() {
    someLabel.text = "SomeLocalizationKey".localized()
  }
}