title: Could use identifierforvendor as identifier?
body: <p>follow this document. identifierforvendor is unique on the same app on the same device. </p>
  
  <p>I want to ask. Is identifierforvendor unique each device?</p>
  
  <p><a href="https://developer.apple.com/reference/uikit/uidevice/1620059-identifierforvendor" rel="nofollow noreferrer">https://developer.apple.com/reference/uikit/uidevice/1620059-identifierforvendor</a></p>