Apple made a hullabaloo over iOS 8's user-accessible privacy controls during itsWWDC keynote, but it now appears that some of the biggest safeguards are under the hood. Security guru Frederic Jacobs has noticed that iOS 8 uses random network identifiers when scanning for WiFi access, and will only reveal a device's true ID when it connects. In other words, hotspot operators can't get your position simply because you're walking by with an iPhone in hand -- you have to sign in first.

http://www.engadget.com/2014/06/09/ios-8-wifi-privacy/