iOS 8 includes another hidden feature that Apple didn’t mention during the WWDC Keynote.

In iOS 8, the Wi-Fi scanning behavior has been changed to use random MAC addresses to prevent marketing and analytics companies from tracking users’ movement in retail stores by following Wi-Fi signals from their smartphones.

In iOS 8, Wi-Fi scanning behavior has changed to use random,locally administered MAC addresses… The MAC address used for Wi-Fi scans may not always be the devices real (universal) address… Once the iOS device is done scanning it will give the real MAC ID.

A number of brick-and-mortar retailers like Nordstrom use this technique to track footfall in stores such as how many came through the doors, how many were repeat visitors, how people move about in stores, and how often they return. The news story about Nordstrom’s efforts at some of its stores did not go down too well with customers as they found it creepy and intrusive. One customer posted on Facebook that it was “way over the line.”

Euclid Analytics, a firm that provides such analytics solution to retailers explains that it collects “the presence of the device, its signal strength, its manufacturer (Apple, Samsung, etc.), and a unique identifier known as its Media Access Control (MAC) address.”

Apple has decided to clamp down on this practise in iOS 8 by generating random MAC addresses while scanning for Wi-Fi networks, which would make it next to impossible for marketing and analytics firms to track users’ movement using the Wi-Fi signal from iOS devices.