What's the easiest way to detect the user's operating system in Rails 3?

Question

Simple Rails app, mostly scaffolding. I want to detect whether the user is using Android or iPhone to access my app. What's the easiest way to do that?

Answer 1

if request.env['HTTP_USER_AGENT'].downcase.match(/android|iphone/)
  puts "yup, its mobile"
end

Answer 2

I know this question is old, but in case this helps someone else, I use this method in application_controller.rb to automatically set the format to :mobile:

before_filter :detect_mobile

protected

def detect_mobile
  request.format = :mobile if mobile?
end

def mobile?
  request.user_agent =~ /iPhone|iPad|Android/i
end

The mobile? method is separate so that you can also use it in your own controllers if you need to do some sort of conditional logic for mobile browsers.