The unique string of numbers that individually identifies each iOS device has typically been used by developers as a way to track their app installations across Apple's user base.
About six months ago, Apple warned developers that their ability to access and use UDIDs would be severely limited and they should begin the process of getting away from UDID usage. Most developers would expect about a year to comply with a major change such as this, but Apple seems to be feeling a bit antsy right now.
Many developers are reporting that apps that continue to use UDIDs are being outright rejected by Apple's App Store approval process.
Because the UDID is most commonly used for analytics, gaming networks, and ad placements in apps, many companies and developers are being affected by the swift changes being made by Apple.
According to Tech Crunch, Playhaven, a company that specializes in monetizing apps, is reporting that several of its customers have already been rejected.
The challenge for developers moving forward will be to find a way to retain unique identification of their app installations so they can continue to serve ads, connect users, and collect analytics properly.
For now, the rejection process is rolling out slowly. Only 2 of the 10 app review teams are rejecting apps for UDID usage. In a week, 4 of the 10 teams will be doing it, ramping up to all 10 teams shortly thereafter, according to Tech Crunch."This is a problem," developer Chris Adamson wrote in a blog post, "because we've all had about six months to get off of UDID, and while that's surely enough to get a simple app migrated -- indeed, I have cases where switching it out is a five-line fix -- it is not necessarily the case that everyone can be expected to have already done this."
Blame it on the excessive media coverage of privacy issues or pressure from Congress to ensure that mobile devices are not tracking users. But, whether it's been enough time or not, it's happening.