Uber was on the brink on being barred by Apple and removed from the iOS app store. In 2105, it was discovered to be flouting Apple rules and guidelines, leading to a make-or-break meeting between company CEO Travis Kalanick and Apple boss Tim Cook.

The New York Times reports that Uber was found to be fingerprinting individual iPhones and tagging them on its systems, with the data remaining even after the Uber app was deleted devices had been erased and reinstalled.

Cook greeted Kalanick with the ominous words, "So, I’ve heard you’ve been breaking some of our rules." It lead to a threat to stop the practice or be removed from the Apple app store entirely.

Uber changed tack and prevented the overnight loss of millions of customers.

That doesn't mean Uber doesn't still fingerprint devices, however, it just does it within Apple's privacy guidelines these days.

TechCrunch reports that the company fingerprints individual devices to ensure they are not tools used for fraudulent means: "This is a typical way to prevent fraudsters from loading Uber onto a stolen phone, putting in a stolen credit card, taking an expensive ride and then wiping the phone - over and over again," a company spokesperson told the site.

"Similar techniques are also used for detecting and blocking suspicious logins to protect our users' accounts. Being able to recognise known bad actors when they try to get back onto our network is an important security measure for both Uber and our users."

Fingerprinting is not used to track users: "We absolutely do not track individual users or their location if they’ve deleted the app."