title: iOS Facebook Login "object nil" crash
body: <p>Working with Facebook 3.7 for iOS, authentication for App.  It works 70% of the time, other 30% crashes.  Seems to have no bearing on whether connected in internet.  In the first method below - populateUserDetails, I check whether dictionary is nil, which I would think would stop this issue, back it still happens.  </p>
  
  <p>Here is my error:</p>
  
  <pre><code>*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** setObjectForKey: object cannot be nil (key: 0_auth_logger_id)'
  </code></pre>
  
  <p>Here is my authentication code:</p>
  
  <pre><code>- (void)populateUserDetails
  {
  if (FBSession.activeSession.isOpen) {
      [[FBRequest requestForMe] startWithCompletionHandler:
       ^(FBRequestConnection *connection,
         NSDictionary&lt;FBGraphUser&gt; *user,
         NSError *error) {
           if (!error || ![user isEqualToDictionary: nil]) {
               // if (!error) {
               self.userNameLabel.text = [user objectForKey:@"email"];
               email = [user objectForKey:@"email"];
               //      self.userProfileImage.profileID = user.id;
  
               if ([facebookUser isEqualToString:@"yes"]){
               [self appendAndSaveData];
               [self performSegueWithIdentifier:@"segueIntroScreenLogin" sender:self];
               }
  
           }
       }];
  }
  }
  
  -(void)viewWillAppear:(BOOL)animated{
  [super viewWillAppear:animated];
  
  if (FBSession.activeSession.isOpen) {
  [self populateUserDetails];
  }
  }
  
  -(void)logoutButtonWasPressed:(id)sender {
  [FBSession.activeSession closeAndClearTokenInformation];
  }
  
  
  - (IBAction)performLogin:(id)sender
  {
   facebookUser = @"yes";
   NSLog(@"IntroScreen, email: %@", email);
   AppDelegate* appDelegate = [UIApplication sharedApplication].delegate;
   [appDelegate openSession];
  
      if([email length] &gt;0){
  
       [self appendAndSaveData];
       [self performSegueWithIdentifier:@"segueIntroScreenLogin" sender:self];
   }
  </code></pre>
  
  <p>}</p>