title: Recording iOS Simulator produces empty files
body: <p>I am trying to record the screen of my iOS 11.4 simulator with <code>xcrun simctl io booted recordVideo recording.mov</code>. This creates a file with that name, but unfortunately that file always has the size of 0 byte. Playing around with the <code>--type</code> parameter did not help either. Occasionally there was a playable file, which also was corrupted to a degree, as this file had a distorted look to it when opened in QuickTime. VLC could not play it at all. </p>
  
  <p>I am using Xcode 9.4.1 on a 2014 MacBook Pro with discrete GPU, so Metal is supported. </p>
  
  <p>Does anyone have suggestions to solve my problem?</p>