title: by whom presenting iOS's privacy dialog
body: <p>if my app is requesting GPS location, there's a dialog shown to user asking permission.
  and my app also check the authorization, if the user not allow use location service, I will also prompt a dialog to notify user to do the settings.</p>
  
  <p>now the question is, when I <code>first</code> launch the app, the user haven't <code>allow</code> yet, but the check code also executed, so it will show a dialog beneath the system privacy dialog. now it has two scenarios:</p>
  
  <ol>
  <li>user click <code>Don't allow</code>, the system dialog dismissed, and my dialog appear, say app don't have permission to locate, that's right.</li>
  <li>but if user click <code>Allow</code>, my will also shown because it's right there, beneath the system's dialog.</li>
  </ol>
  
  <p>I now can only put the two part code different place, but is there a better or more reasonable way to solve this? which is, if user clicked allow, I will know.</p>
  
  <p>some thoughts:
  1. if I can know there's a system's privacy dialog been presenting (not a better way, because I just want to know location privacy
  2. how to know the location privacy dialog's presenter, so I will use it to check if it has presenting a dialog
  3. how to know what action did user do after the privacy dialog is shown can user clicked to dismiss.</p>