title: facebook-ios-sdk logout question
body: <p>I have seen a lot of questions here regarding the Facebook Graph API but I still haven't find a solution for simple 'login'/'logout' operations using it. Looks like the Single Sign-On style is causing more confusion than benefits.</p>
  
  <p>I'd like to know if it is possible have the following situation:</p>
  
  <ol>
  <li>Enter in the app (no <code>accessToken</code>/<code>expirationDate</code> created).</li>
  <li>Perform a login using SSO by calling <code>authorize:delegate:</code> method (application goes background and the login is made in the 'global' scope (Facebook App/Mobile Safari), asking for the user credentials.</li>
  <li>Enter back in the app (now logged in, both <code>accessToken</code> and <code>expirationDate</code> are saved to <code>NSUserDefaults</code>).</li>
  <li>Perform a logout by calling the <code>logout:</code> method (now logged out, both <code>accessToken</code> and <code>expirationDate</code> are removed from <code>NSUserDefaults</code>)</li>
  <li><strong>Attempt to perform a login again, with exactly the same steps done in 2.</strong></li>
  </ol>
  
  <p>I realize that when I call <code>logout:</code>, I do really log out from Facebook (<code>accessToken</code> is invalidated) from my App scope, not from the <code>global</code> scope (Facebook App/Mobile Safari). In <strong>5.)</strong> when I try to log in again, the application goes to background and the login attempt is made again in Facebook App/Mobile Safari as usual, however I'm getting a screen saying that I'm already logged in:</p>
  
  <blockquote>
    <p>You have already authorized <code>...</code>. Press "Okay" to continue.
    Logged in as <code>...</code> (Not You?).</p>
  </blockquote>
  
  <p>It's a strange behavior for the user that has just logged out in my App.
  My question is:  </p>
  
  <p>"Can I <strong>really</strong> log out from facebook (I mean 'global' scope) from inside my App? This  would affect other apps using the facebook credentials too. However, if I can't to do this, how can I avoid the 'strange behavior' describe above?</p>
  
  <p>Thanks</p>