Will you please help me to fix this below mentioned issue getting from Apps store
Apps are not permitted to access the UDID and must not use the uniqueIdentifier method of UIDevice. Please update your apps and servers to associate users with the Vendor or Advertising identifiers introduced in iOS 6. If method names in your source code match the private Apple APIs listed above, altering your method names will help prevent this app from being flagged in future submissions. In addition, note that one or more of the above APIs may be located in a static library that was included with your app. If so, they must be removed.
If you think this message was sent in error and that you have only used Apple-published APIs in accordance with the guidelines, send the app's nine-digit Apple ID, along with detailed information about why you believe the above APIs were incorrectly flagged, to appreview@apple.com. For further information, visit the Technical Support Information page.
Once these issues have been corrected, go to the Version Details page and click "Ready to Upload Binary." Continue through the submission process until the app status is "Waiting for Upload." You can then deliver the corrected binary.