title: iOS13 can't support the background update notification?
body: <p>iOS13 can't support the background update notification.Is this an OS-level bug?
  And when app enter background,the Xcode warning shows:</p>
  
  <blockquote>
    <p>Can't end BackgroundTask: no background task exists with identifier 1
    (0x1), or it may have already been ended. Break in
    UIApplicationEndBackgroundTaskError() to debug.</p>
  </blockquote>