title: siri shortcut button (INUIAddVoiceShortcutButton) shows wrong title when have multiple shortcuts (NSUserActivity)
body: <p>I've 2 siri shortcuts in my App. 
  I use NSUserActivity to donate these shortcuts. I've also created 2 NSUserActivityTypes in my info.plist. </p>
  
  <p>There are 2 view controllers which handle these shortcuts (1 view controller for 1 shortcut).</p>
  
  <p>If I add 1 siri shortcut from 1 view controller and then go to 2nd view controller the native siri shortcut button (<code>INUIAddVoiceShortcutButton</code>) on 2nd view controller automatically picks the first shortcut (created from 1st view controller) and shows "Added to Siri" with suggested phrase instead of showing "Add to Siri" button. I double checked that each <code>NSUserActivity</code> has different identifier but still somehow its picks the wrong shortcut.</p>
  
  <p>View Controller 1:</p>
  
  <pre><code>let userActivity = NSUserActivity(activityType: "com.activity.type1")
  userActivity.isEligibleForSearch = true
  userActivity.isEligibleForPrediction = true
  userActivity.title = shortcut.title
  userActivity.suggestedInvocationPhrase = suggestedPhrase
  
  let attributes = CSSearchableItemAttributeSet(itemContentType: kUTTypeItem as String)
  attributes.contentDescription = description
  userActivity.contentAttributeSet = attributes
  let shortcut = INShortcut(userActivity: userActivity)
  let siriButton = INUIAddVoiceShortcutButton(style: .whiteOutline)
  siriButton.translatesAutoresizingMaskIntoConstraints = false
  siriButton.shortcut = shortcut
  self.view.addSubview(siriButton)
  </code></pre>
  
  <p>View Controller 2:</p>
  
  <pre><code>let userActivity2 = NSUserActivity(activityType: "com.activity.type2")
  userActivity2.isEligibleForSearch = true
  userActivity2.isEligibleForPrediction = true
  userActivity2.title = shortcut.title
  userActivity2.suggestedInvocationPhrase = suggestedPhrase
  
  let attributes = CSSearchableItemAttributeSet(itemContentType: kUTTypeItem as String)
  attributes.contentDescription = description
  userActivity2.contentAttributeSet = attributes
  
  let shortcut = INShortcut(userActivity: userActivity2)
  let siriButton = INUIAddVoiceShortcutButton(style: .whiteOutline)
  siriButton.translatesAutoresizingMaskIntoConstraints = false
  siriButton.shortcut = shortcut
  self.view.addSubview(siriButton)
  </code></pre>
  
  <p>A similar thing happens when I delete the App and reinstall without deleting the shortcuts from Phone's Settings App.</p>