title: -stringByAppendingString: not working
body: <p>I need to concatenate two NSStrings , I wrote the code below:</p>
  
  <pre><code>NSString *reverseResult = [[NSString alloc] initWithFormat:@""];
  NSString *zero = [[NSString alloc] initWithFormat:@"0"];
  NSString *one = [[NSString alloc] initWithFormat:@"1"];
  int modRes;
  while (num != 0) {
      modRes = num;
      modRes = num % 2;
      if (modRes == 0)
          [reverseResult stringByAppendingString:zero];
      else
          [reverseResult stringByAppendingString:one];
      num = num / 2;
  }
  </code></pre>
  
  <p>When I debug the code I see that the "stringByAppendingString" is not doing what I need (reverseResult stays @"", even though it gets to that row).</p>
  
  <p>Is there something wrong with the code?</p>