As per Apple they will not accept new apps or app updates that access UDIDs. So what would the alternative for this as iam running many apps on app store. If i need to update them what would be the easiest solution?
See Below:-
Using Identifiers in Your Apps (March 21, 2013)
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. You can find more details in the UIDevice Class Reference.
Thanks.