Open Radar

 
The sample code  obtained different mac address to address that was used to validate the receipt. Due to this customer experiences unrecoverable issue with message that app is damaged. Airplay/reboot did not solve the problem.
Sample code: 
https://developer.apple.com/documentation/appstorereceipts/validating_receipts_on_the_device


Upon checking internal Apple implementation in AppleMediaServices.framework (+[AMSDevice macAddressData]) I have noticed differences that caused this problem:

Sample Code

if wantBuiltIn == CFBooleanGetValue(isBuiltIn) {
  return candidate
}

Internal Code

if CFBooleanGetValue(isBuiltIn) == true {
  return candidate
} else if wantBuiltIn == false {
  return candidate
} else { //interface is not build in but we want build in
  continue
}

Another difference is:

guard let service = io_service(named: "en0", wantBuiltIn: true)
?? io_service(named: "en1", wantBuiltIn: false) //instead of true
?? io_service(named: "en0", wantBuiltIn: false)

Due to the difference I would even rename wantBuiltIn to shouldFailIfNotBuiltIn

The same differences are also present in the new implementation (suspected that it will move to new framework)
AMSCore::NetworkUtils::CopyInterfaceMACAddress(unsigned int)


While technically the sample code is correct, it’s not what Apple is using behind the curtains.