Apple let it be known back in August of 2011 that they'd be deprecating developer access to UDID ( Universal Device Identifier), they've now taken the next step and begun actively rejecting App Store apps that use it. The fine developers of Tweetbot have reported that one of their latest updates was rejected from Apple for collecting UDID information without getting user consent first. What does this mean for apps like Tweetbot?

[UDIDs] allowed us to restore push notifications settings after Tweetbot was deleted and re-installed. With this new change in place this is no longer possible, if you delete and re-install Tweetbot you’ll have to setup your push notification settings again.

The UDID is 40 characters that are unique to your iPhone and iPad, used most generally by developers to provision pre-release apps through the App Store. Now developers will need to create their own unique ID within the app and store it in iCloud.

Ultimately, it's good news that Apple is making sure that developers aren't easily getting a hold on potentially sensitive data like UDIDs; iOS users are a little on edge about privacy after that Path incident.

This might also explain the speed with which Apple went from deprecating the UDID collection to outright rejecting apps. Typically something deprecated in one iOS version will be removed in a later version, giving developers time and an expectation for when they need to have an alternative approach in place. This has led some developers, including

Source: Tapbots, Subfurther