Determines whether or not the user is a mobile device

mobile_device.rb

  def prepare_for_mobile
    session[:mobile_param] = params[:mobile] if params[:mobile]
    request.format = :mobile if mobile_device?
  end

  def mobile_device?
    return (session[:mobile_param] == "1") if session[:mobile_param]
    request.user_agent.to_s.downcase =~ Regexp.new(
      'palm|blackberry|nokia|phone|midp|mobi|symbian|chtml|ericsson|minimo|' +
      'audiovox|motorola|samsung|telit|upg1|windows ce|ucweb|astel|plucker|' +
      'x320|x240|j2me|sgh|portable|sprint|docomo|kddi|softbank|android|mmp|' +
      'pdxgw|netfront|xiino|vodafone|portalmmm|sagem|mot-|sie-|ipod|up\\.b|' +
      'webos|amoi|novarra|cdm|alcatel|pocket|ipad|iphone|mobileexplorer|' +
      'mobile'
    )
  end