@version ||= version

# -*- encoding : utf-8 -*-
class InterfaceBaseController < ActionController::Base

  private
  def set_version
    version = params[:version] || '1.8.0'
    ua = params[:ua] || ''

    @version = if ua == 'xxx'
                 '1.8.0' if version >= '2.1.0'
               elsif ua == '111'
                 '1.8.0' if version >= '1.1.1'
               end 

    @version ||= version
  end 

end

before_filter :set_version, only: [:all_channels]

#可以直接使用@version来替代params[:version]