title: iOS UUID different for same app depending if installed through xcode or testflight
body: <p>I'm finding that the UUID I get is different depending on whether the app is directly installed by xcode (which I do during development) or through testflight.</p>
  
  <p><code>let uuidstring = UIDevice.current.identifierForVendor!.uuidString</code></p>
  
  <p>Is it possible to get a UUID that is the same in both cases?</p>
  
  <p>Ideally a UUID that is truly a unique <em>device</em> identifier, and doesn't change if the app is removed and added, which seems to change the UUID currently.</p>