title: How to use iOS CNCopyCurrentNetworkInfo to read WIFI signal strength (RSSI)?
body: <p>I need to get the signal strength of an iPHone's present WiFi connection.
  (This is just a development experiment and not an app that will go to app store.)</p>
  
  <p>I've searched CNCopyCurrentNetworkInfo reference but can't see how to do it.</p>
  
  <p>Needs to be for iOS 8.</p>