title: Find nearby users of an app (iPhone and Android)
body: <p>I am working on an app that has an iPhone version as well as an Android version. </p>
  
  <p>My goal is...</p>
  
  <ul>
  <li>display a list of nearby users of my app (iPhone app users and Android app users). Lets say a list users which are currently within 1 mile or 2 miles radius and are currently using my app.</li>
  <li>This list will display on both apps, iPhone app and Android app.</li>
  <li>App will update the list when user clicks a Refresh button.</li>
  </ul>
  
  <p>My question is...</p>
  
  <ul>
  <li>What is the best way to accomplish above stated goal? Do I need to periodically send current GPS location of all users of app from their Droids and iPhones to our web server?</li>
  </ul>
  
  <p>To make my question more clear...</p>
  
  <ul>
  <li>I have an algorithm to find out the places/users within a given range (1 mile or 2 miles radius etc), so PLEASE DON'T TELL ME how to find users within a given range.</li>
  <li>I know how to get current location of iPhone and Droid devices, so PLEASE DON'T TELL ME how to get updated location of an iPhone or Android device.</li>
  <li>I know that this is a privacy issue. Therefore app will ask for user's permission to send their location to our web server, so PLEASE DON'T TELL ME about privacy concerns users or Apple may have.</li>
  <li><strong>JUST TELL ME</strong> how to best maintain updated list of Geo Locations of my app users on the web server? The best, proven approach!</li>
  <li>Let me know if my question still needs clarification.</li>
  </ul>
  
  <p>Thanks and best regards</p>