title: Does the iOS Facebook in app browser behave differently to Safari?
body: <p>I've just taken a Facebook app live (ie: it's a web app that lives at apps.facebook.com). The app is a simple form that allows you to vote for one of four options. When submitting the form for the vote we also capture the FB ID in order limit the user to 4 votes per day.</p>
  
  <p>When testing this app in sandbox mode as well as live in any browsers, the app functions fine. It even has exception handling in the edge cases where the user is not FB authenticated etc.</p>
  
  <p>The issue we have encountered is that when a user visits the app from within the iOS Facebook app, the link opens within the Facebook in app browser (based on the iOS UIWebView component I believe). When using it from this environment, when the form submits our server is producing a 500 error.</p>
  
  <p>Now I know that the 500 error will be nothing to do with facebook since it is our application code, but my confusion arises from the fact that this only happens from the Facebook in app browser. We are currently going about trying to determine the nature of the 500 error (we do not have access the production environment and custom errors have been switched off).</p>
  
  <p><strong>My question is this: Does the Facebook in app browser behave differently or do things differently than the standard UIWebView or iOS Safari?</strong> </p>
  
  <p>I am thinking of differences such as interfering with POST data, clearing FB login credentials etc.</p>