title: How to stop enumerating attributes of a NSAttributedString?
body: <p>In the documentation of the <code>enumerateAttribute</code> method it is said, regarding the <code>stop</code> argument of the block, that:</p>
  
  <blockquote>
    <p>The block can set the value to true to stop further processing of the set.</p>
  </blockquote>
  
  <p>However, inside the block the <code>stop</code> argument is a <code>let</code> and I can't set it to <code>true</code>.</p>
  
  <p>I need to stop enumerating after the first attribute occurrence found. How could I do that?</p>