title: Facebook logout not working properly through the Facebook Connect iPhone API
body: <p>I am executing the following code to logout of Facebook from my iPhone application:</p>
  
  <pre><code>if ([mFacebook isSessionValid]) {
      [mFacebook logout];
  }
  </code></pre>
  
  <p>This code runs successfully and the delegate is called after this in which I am clearing the access token:</p>
  
  <pre><code>- (void)fbDidLogout 
  {
      NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
      [defaults removeObjectForKey:@"FBAccessTokenKey"];
      [defaults removeObjectForKey:@"FBExpirationDateKey"];
      [defaults synchronize];
  }
  </code></pre>
  
  <p>But when I again log in to Facebook, it does not ask for username and password.</p>
  
  <p>What am I doing wrong?</p>