Friday, August 19, 2011 at 4:42 pm.

Apple quietly removes UDID API, many developers will have to scramble

Specifically, I’m told that Apple has unexpectedly deprecated the API to access an iOS device’s UDID, or unique device identifier, according to an iOS developer who doesn’t want to be named as the information is under NDA.

Developers use this unique device ID to anonymously build up information about a device and its owner, which can be tracked across sessions and between multiple apps. (So it would seem that Apple did this as a privacy precaution.)

According to this developer, a variety of companies have been using the UDID as a way to track users without requiring a login, including game networks, analytics companies, ad networks, and others. (See this post about how widespread this activity is and potential privacy vulnerabilities.)

Developers will now have to scramble to figure out new ways to do this, and may struggle to identify common users between multiple apps. And old user data they have will no longer be useful.

While this seems like a fair protection of iOS users’ privacy, this developer believes Apple itself may continue to use UDIDs to track users, particularly for its GameCenter network and iAd ad network, without offering the feature to third-party competitors.

I’ve reached out to Apple for comment and will update if I hear back.