Using Variant for creating multi device websites

  # Add to Gemfile
  gem 'mobvious'

  # Tell your app to use Mobvious::Manager as Rack middleware.
  # If you use Rails, simply add this into your config/application.rb
  config.middleware.use Mobvious::Manager

  # Add strategies to detect device
  Mobvious.configure do |config|
    config.strategies = [
      Mobvious::Strategies::Cookie.new([:mobile, :tablet, :desktop]),
      Mobvious::Strategies::MobileESP.new(:mobile_tablet_desktop)
    ]
  end

# app/application_controller.rb
class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception

  before_action :detect_device_variant

  private

  def detect_device_variant
    case request.env['mobvious.device_type']
    when :desktop
      request.variant = :desktop
    when :tablet
      request.variant = :tablet
    when :mobile
      request.variant = :phone
    end
  end

end

# specify by format.html
class HomeController < ApplicationController
  def index
    @comics = Comic.all
    respond_to do |format|
      format.json
      format.html               # /app/views/posts/show.html.erb
      format.html.phone         # /app/views/posts/show.html+phone.erb
      format.html.tablet        # /app/views/posts/show.html+tablet.erb
    end
  end
end

# specify by variant type inside format.html block
class HomeController < ApplicationController
  def index
    @comics = Comic.all
    we can also define the render method as below
    respond_to do |format|
      format.html do |variant|
        variant.tablet
        variant.phone
        variant.desktop
        variant.none
      end
    end
  end
end