Customize navigation bar using Rubymotion + ProMotion

SampleScreen.rb

class SampleScreen <  Promotion::Screen
  title "Sample" #pass empty string if you dont want to display title in nav_bar
  
  def on_load
    customize_nav_bar
  end
  
  private
  def customize_nav_bar
    #set nav bar buttons using ProMotion
    set_nav_bar_button :left, {action: :go_to_browse, image: 'btn_back'.uiimage}
   
    nav_bar = self.navigationController.navigationBar
    #change tintColor
    nav_bar.tintColor = UIColor.whiteColor # if you are using sugarcube, you can use :white.uicolor
    #add background image
    nav_bar.setBackgroundImage('some_image_background'.uiimage, forBarMetrics: UIBarMetricsDefault) # see rubymotion docs: http://www.rubymotion.com/developer-center/api/UINavigationBar.html
    
    
    #add some buttons with image
    btn_1 = UIBarButtonItem.alloc.initWithImage('btn_1'.uiimage, style: UIBarButtonItemStylePlain, target: self, action: 'btn_1_clicked')
    btn_2 = UIBarButtonItem.alloc.initWithImage('btn_2'.uiimage, style: UIBarButtonItemStylePlain, target: self, action: 'btn_2_clicked')
    self.navigationItem.rightBarButtonItems = [btn_1, btn_2]
  end
  
  def go_to_browse
    open BrowseScreen.new
  end
  
  def btn_1_clicked
    #add your code here
  end
  
  def btn_2_clicked
    #add your code here
  end
end