title: How to detect ios push notification permissions/settings programmatically
body: <p>In Notification settings (Settings->Notifications->AnyAppName), there are 5 items and each has a switch button, <code>Sounds</code>,<code>Badge App Icon</code>, <code>Show on Lock Screen</code>, <code>Show in History</code>, <code>Show as Banners</code>. </p>
  
  <p>I am using <code>[[[UIApplication sharedApplication] currentUserNotificationSettings] types]</code> to get user's settings and promote corresponding alert to use.
  It may return value <code>0~7</code> represents any combination of <code>Sound</code>, <code>Badge</code> and <code>Banners</code>. The question is, are we able to detect the states of <code>Show on Lock Screen</code>, <code>Show in History</code>?</p>
  
  <p>Also, at the bottom of the setting page, theres is an <code>OPTIONS</code> option called <code>Show Previews</code>, it has three options: <code>Always(Default)</code>, <code>When Unlocked</code> and <code>Never</code>. Are we able to get user's setting programmatically for this?</p>