title: "Find my friends" style GPS (remotely ping for location)
body: <p>In the "find my friends" ios app, a friend can ask for another person's location.  Find my friends grabs the location in the background and the location services arrow  appears  momentarily.  I am mainly  concerned with the fact that the GPS arrow indicator is only shown when the user is pinged by a friend (does not remain on).</p>
  
  <p>My intended scenario: Bob opens the app and pings his friend John for John's location.  John's phone momentarily shows the GPS arrow and in the background, sends back his location to the server where we can send info back to Bob.</p>
  
  <p>What is the basic strategy for accomplishing this?  Is there some way to wake the app in the background to grab location?</p>
  
  <p>I don't want to use something like significant location changes as I only want to grab user location when a specific action happens (a friend pings them).</p>
  
  <p>Thanks so much!!</p>