title: Not scanning credit/debit cards using card.io
body: <p>I am using <code>card.io_ios_sdk_3.8.0</code>, I followed exactly what is mentioned in <a href="https://github.com/card-io/card.io-iOS-SDK" rel="nofollow">https://github.com/card-io/card.io-iOS-SDK</a>. I am unable to scan credit or debit cards (VISA , Discover, etc).</p>
  
  <p>I get "NSScanner: nil string argument".</p>
  
  <p>I know I am making a mistake but I don't know how to track that. Is there any country based?</p>
  
  <pre><code>      - (IBAction)scanCard:(id)sender
        {
                CardIOPaymentViewController *scanViewController = [[CardIOPaymentViewController alloc] initWithPaymentDelegate:self];
                scanViewController.appToken = @"&lt;I have entered my app token&gt;"; // get your app token from the card.io website
                [self presentViewController:scanViewController animated:YES completion:nil];
         }
  
          - (void)userDidProvideCreditCardInfo:(CardIOCreditCardInfo *)info inPaymentViewController:(CardIOPaymentViewController *)scanViewController 
         {
               // The full card number is available as info.cardNumber, but don't log that!
               NSLog(@"Received card info. Number: %@, expiry: %02i/%i, cvv: %@.",           info.redactedCardNumber, info.expiryMonth, info.expiryYear, info.cvv);
              // Use the card info...
  
             if(info.cardNumber!=Nil &amp;&amp; ![info.cardNumber isEqualToString:@""] &amp;&amp; !      [info.cardNumber isKindOfClass:[NSNull class]])cardNumber.text = info.cardNumber;
             if(info.cvv!=Nil &amp;&amp; ![info.cvv isEqualToString:@""] &amp;&amp; ![info.cvv isKindOfClass:[NSNull class]])cvvno.text = info.cvv;
             if(info.expiryMonth!=0)[self getCorrectMonth:[NSString stringWithFormat:@"%02i",info.expiryMonth]];
             if(info.expiryYear!=0) year.text = [NSString stringWithFormat:@"%i",info.expiryYear];
  
             [scanViewController dismissViewControllerAnimated:YES completion:nil];
          }
  </code></pre>
  
  <p>I am not sure , whether its related to acknowledgements properly added or not.</p>