title: How to set a corner radius for NSAttributedString's background?
body: <p>I want to set a corner radius for partial text on UILabel. I've got the range.<br>
  The following code set the background color, but it gonna be a rectangle background.</p>
  
  <p>So, my problem is <strong>how to set a corner radius to it</strong>?</p>
  
  <pre><code>string.setAttributes([NSBackgroundColorAttributeName: UIColor.red], range: range)
  </code></pre>
  
  <p>Thank you for any suggestion.</p>