title: rails oauth and using FB mobile app if we are mobile
body: <p>I am using the facebook omniauth gem and would like to solve the following simple problem:</p>
  
  <p>In case a user browses my rails app mobile (e.g. via iPhone, iPad) I would like him to authenticate via his FB app on his device. Currently the auth happens via the browser version of Facebook which is a weird user experience.</p>
  
  <p>I was looking into the configuring parameters via <a href="https://github.com/mkdynamic/omniauth-facebook">https://github.com/mkdynamic/omniauth-facebook</a> but could not find any help there.</p>
  
  <p>I assume I need to edit my omniauth.rb file which currently looks like this:</p>
  
  <pre><code>Rails.application.config.middleware.use OmniAuth::Builder do
       provider :facebook, 'XXXXXXX', 'XXXXXX',
       :scope =&gt; 'email'
    end
  </code></pre>
  
  <p>Thanks</p>