title: FBSDKInternalUtility Exception using FBSDK framework in objectiveC
body: <p>I'm using <code>FBSDKCoreKit</code> framework for custom login. I followed the documentation perfectly. I'm using <code>FBSDKLoginManager</code> for Login.I'm unable to find why this exception was coming  and getting exception as 
  <code>[FBSDKInternalUtility JSONStringForObject:error:]:</code> unrecognized selector sent to class.please help me to solve this issue.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>[FBSDKProfile enableUpdatesOnAccessTokenChange:YES];
  FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init];
  [login logInWithReadPermissions:@[@"email",@"public_profile"] handler:^(FBSDKLoginManagerLoginResult *result, NSError *error) {
      if (error)
      {
  
      } else if (result.isCancelled)
      {
  
      } else
      {
          NSLog(@"%@",result);
          if ([result.grantedPermissions containsObject:@"email"])
          {
              if ([FBSDKAccessToken currentAccessToken])
              {
                  [[[FBSDKGraphRequest alloc] initWithGraphPath:@"me" parameters:nil]
                   startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection, id result, NSError *error) {
                       if (!error) {
  
                           NSLog(@"find result=%@",result);
                       }
                   }];
              }
  
          }
      }
  }];
  </code></pre>