title: iOS proximity & GPS measure the distance
body: <p>I am developing an app where I require to alert user if he move more than 20 meters from his checking location. I am planning to use proximity sensor for this development. However I found this document.</p>
  <p><a href="http://developer.apple.com/library/ios/#documentation/userexperience/conceptual/LocationAwarenessPG/CoreLocation/CoreLocation.html" rel="nofollow noreferrer">http://developer.apple.com/library/ios/#documentation/userexperience/conceptual/LocationAwarenessPG/CoreLocation/CoreLocation.html</a></p>
  <p>It says</p>
  <blockquote>
  <p>&quot;The specific threshold distances are determined by the hardware and
  the location technologies that are currently available. For example,
  if Wi-Fi is disabled, region monitoring is significantly less
  accurate. However, for testing purposes, you can assume that the
  minimum distance is approximately 200 meters.&quot;</p>
  </blockquote>
  <p>If I use GPS distance it will take considerable power utilization. Am I developing on wrong path? Appriciate your kind sugesstions.</p>