Companies are issued Enterprise Certificates to allow their developers to test iOS apps internally without the need to go through that painstaking process. Apple expressly forbids such uses of enterprise certificates; they're created to allow companies to develop and distribute apps purely for internal use or limited beta testing.
Google's also been sneaking in through the back door, using the system to run an app called Screenwise Meter that sounds a lot like Facebook's Research virtual private networking (VPN) app. Just like Facebook, the app relied on Apple's enterprise program that allows distribution of internal apps within the company.
Facebook spokesman Andy Stone did not immediately respond to other questions.
Apple did not respond to a request for comment. Apple CEO Tim Cook has been outspoken about his opposition to companies whose business model is based on analyzing massive quantities of user data.
Facebook app for iOS users has been updated to version 206.0, and while it brings under the hood improvements for other iPhone users, it also introduces native higher resolution support.
"The Screenwise Meter iOS app should not have operated under Apple's developer enterprise program - this was a mistake, and we apologize". The latter was somewhat proactive, pulling the app itself before Apple could react.
Facebook has now threatened users of the Research app claiming it that it wasn't secret.
While both research programs let the internet giants track activity, Facebook's was more invasive because the company could see much more traffic from users' phones.
Fast on the heels of Apple kicking Facebook Research out of the program on Tuesday, so too did Screenwise Meter get the heave-ho.
The world's biggest social network is in hot water over privacy rights yet again, with another controversy involving user data revealed this week.
Thus far, Apple has not indicated whether it will be ramping up its policing of companies' use of enterprise certificates as a result of Facebook and Google's actions.
Apple has in the past revoked enterprise developer certificates from rogue developers who'd used them to distribute malicious iOS apps outside Apple's walled-garden.
A Google spokesperson told Download.com: "I can confirm that our internal corporate apps have now been restored".
"There was nothing "secret" about this; it was literally called the Facebook Research App", Arielle Argyres, a Facebook spokeswoman, said in a statement.