title: Logout from Flickr/Facebook - iOS
body: <p>I login to these social networking websites not using safari, but using a <code>UIWebView</code> inside the app. But once logged in, I have not been able to log them out.
  (Trying to use fb  SDK and ObjectiveFlickr, but their logout methods are also not helping.)</p>
  
  <p>I tried removing cookies for 'login.yahoo.com' and 'facebook.com' but it didn't help. I want the login screen to come up, but instead of that, it directly asks for authentication.</p>