05-29-2017, 04:45 AM
It's to make the top buttons accessible for the short handed people. It's a feature called Reachability. As you mentioned a side swipe will activate it. Along with a double tap. Not double press. You can disable it.
https://www.google.com/amp/www.iphonehac...6.html/amp
https://www.google.com/amp/www.iphonehac...6.html/amp