Simple iPhone User Agent detection with Rails

There are a lot of methods for detecting user agents, but if you just want to use a different app layout in your rails app for iPhone users, here’s how we do it.

class ApplicationController < ActionController::Base

  ...
  
  layout :application_layout

  # detect UA for iPhone users
  def application_layout
    @browser_name ||= begin
      ua = request.env['HTTP_USER_AGENT'].downcase
      if ua.index('iphone')
        'application.iphone'
      else
        'application'
      end
    end
  end
  
end

It’s important to note that we did have to define layout :application_layout Rails will choose this as a default, but since we have to override it’s default we’ll need to state it again here.

Now we just need those two files, application.iphone.html.erb and application.html.erb in views/layouts.