title: Get HTML in UITextView
body: <p>I display html in <code>UITextView</code> by:</p>
  
  <p><code>[self.textView setValue:@"&lt;b&gt;Content&lt;/b&gt;" forKey:@"contentToHTMLString"];</code>, </p>
  
  <p>After editing content in <code>UITextView</code>, I want to get content include html so I use:</p>
  
  <p><code>[self.textView valueForKey:@"contentToHTMLString"];</code> but app crash, how to fix it?</p>