hoge_screen.rb

class HogeScreen < TabScreenBase
  tab_icon icon: "fuga_image"
end

tab_screen_base.rb

class TabScreenBase < PM::Screen
  class << self
    def config
      @config ||= {}
    end

    def tab_icon(args)
      config[:tab_icon] = args
    end
  end

  def config
    self.class.config
  end

  def on_create(args={})
    set_tab_bar_item(config[:tab_icon])
  end
end