title: How does WhatsApp handle silent push notifications on iOS when app was killed by user?
body: <p>From what I've learned, silent push notifications do not call <code>application:didReceiveRemoteNotification:fetchCompletionHandler:</code> when the user killed the app via multitasking UI. But when looking at WhatsApps behavior, I do not understand how they manage to do the following:</p>
  
  <ul>
  <li>mute a channel</li>
  <li>force quit WhatsApp</li>
  <li>receive a message in the muted channel</li>
  <li>badge is shown</li>
  <li>what's even more surprising =></li>
  <li>without launching WhatsApp, start Airplane mode</li>
  <li>now launch WhatsApp => the text is shown at the right place</li>
  </ul>
  
  <p>this means that WhatsApp somehow manages it to handle the receiption of the push notification although the app is killed. Does anyone have an idea how? With <code>.badge</code>, <code>.alert</code>, ...?</p>