title: Facebook SDK 3.1 for iOS, completion handler is never called when logging in through app switching
body: <p>I'm developing an app that has to post some info to facebook. When I call</p>
  
  <pre><code>[[FBSession activeSession] openWithCompletionHandler:^(FBSession *session, FBSessionState status, NSError *error) {
              [self publishFacebookStory];
          }];
  </code></pre>
  
  <p>or</p>
  
  <pre><code>[FBSession openActiveSessionWithPublishPermissions:publishPermissions defaultAudience:FBSessionDefaultAudienceEveryone allowLoginUI:YES completionHandler:^(FBSession *session, FBSessionState status, NSError *error) {
          if (!error) {
              [self publishFacebookStory];
          }
      }];
  </code></pre>
  
  <p>the app switches to safari, I get a message saying that the app has already been authorised. I press okay and it switches back to my app but the completion handlers are never called and I still dont have a valid access token at this point.</p>
  
  <p>Any ideas? Any help is appreciated.</p>
  
  <p>Thanks.</p>