title: NSAttributedString crashes on IOS 6.1
body: <p>I use the NSAttributedString for 2 things:</p>
  
  <p>1.To fill a UITextView with a HTML format string</p>
  
  <p>2.To resize that TextView depending on the length of the content</p>
  
  <pre><code>NSAttributedString *attributedString = [[NSAttributedString alloc] initWithData:[MyHTMLString dataUsingEncoding:NSUnicodeStringEncoding] options:@{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil];
  
  myTextView.attributedText = attributedString;
  
  UITextView *calculationView = [[UITextView alloc] init];
  [calculationView setAttributedText:attributedString];
  CGSize size = [calculationView sizeThatFits:CGSizeMake(screenWidth,FLT_MAX)];
  
  CGRect frame_summary = CGRectMake(0, y, size.width, size.height);
  myTextView.frame = frame_summary;
  </code></pre>
  
  <p>And it works great on IOS 7.1 but on IOS 6.1 crashes at the first line(EXC_BAD_ACCES)</p>
  
  <p>As far as I Know NSAttributedString works on IOS 6. </p>
  
  <p>Any clue? </p>
  
  <p>And finally any advice or any alternative to use on IOS 5?</p>
  
  <p>Thanks in advance</p>