title: Why is the NSUserActivity contentAttributeSet nil when opening via Spotlight?
body: <p>I'm computing a NSUserActivity for when I view a specific screen in my app.  (Doesn't matter what, imagine a Location)</p>
  
  <p>I set a lot of information about this activity/location using the contentAttributeSet.</p>
  
  <p>When I visit this screen over and over, I set the viewController's userActivity property to this derived activity, and also call <code>becomeCurrent()</code> on it.</p>
  
  <p>Eventually Siri will suggest that shortcut in Spotlight.  As expected and desired.  I tap on that, it launches my app and calls:</p>
  
  <pre><code>func application( _ application: UIApplication,
                        continue userActivity: NSUserActivity,
                        restorationHandler: @escaping ([UIUserActivityRestoring]?) -&gt; Void) -&gt; Bool
  </code></pre>
  
  <p>however, the <code>.contentAttributeSet</code> property will be nil. </p>
  
  <p>Why?  Have I not understood something here?  I guess any data I need to access later should be in the userInfo dictionary?  That works (as long as I don't set webpageURL)</p>