Starting May 1, the App Store will no longer accept new apps or app updates that access UDIDs. Please update your apps and servers to associate users with the Vendor or Advertising identifiers introduced in iOS 6.The use of UDIDs has privacy concerns for users, and developers were aware that this change was coming. In March of last year, Apple began rejecting applications that accessed UDIDs. That was six months after first warning developers that it would be deprecating the use of UDIDs (in the iOS 5 beta).
Apple has been recommending that developers use the Advertising Identifier, introduced with iOS 6, instead of the UDID. With this change, on May 1, developers will have no choice but to switch.
Also starting on May 1, new apps and updates submitted to the App Store must be built for iOS devices with a Retina display; iPhone apps must support the 4-inch iPhone 5 display. Apple's developer website said:
Starting May 1, new apps and app updates submitted to the App Store must be built for iOS devices with Retina display and iPhone apps must also support the 4-inch display on iPhone 5.Apple added, though, that apps already in the App Store -- sans an update, of course -- will not be booted out of the iOS marketplace.