title: How to make Only one device login at a time in AWS Userpool iOS?
body: <p>I have an application in which user can log in/signup with Mobile Number and OTP. I have used AWS UserPool for this functionality.</p>
  
  <p>But I want that Only one user can log in at a time. </p>
  
  <p>Suppose in device 1 user login with the mobile number: +9197XXX XXXXX
  then if in device 2 user login with the same mobile number: +9197XXX XXXXX</p>
  
  <p>Then the first device should be logged out automatically.</p>
  
  <p>How should i achieve this in AWS Userpool??</p>