How does Pushbullet for iOS manage to access and show all of iOS notifications on other devices?

The new version of Pushbullet app (http://ift.tt/1e2Vu8n) for iOS and Mac can show you all the notifications you get on your phone inside their Mac app. Not just the notifications going to the app itself - all notifications from all applications. How did they manage to do that? I can't figure out which APIs they are using to do this.