gistfile.rb

Teacup.handler UINavigationBar, :backgroundImage do |styles|
  styles.each do |metric, image|
    case metric
    when UIBarMetricsDefault, :portrait
      self.setBackgroundImage(image && image.uiimage, forBarMetrics:UIBarMetricsDefault)
    when UIBarMetricsLandscapePhone, :landscape
      self.setBackgroundImage(image && image.uiimage, forBarMetrics:UIBarMetricsLandscapePhone)
    end
  end
end