V2Iso15693 invalid tag ID (iOS)

[Megatron4537]

On Android reading an NfcV (ISO15963 on iOS) tag will return a tag with an id AD3C117E000104E0

reading the same tag on iOS using the V2Iso15963 API to get the tag's ID will return a tag with an id E00401007E113CAD

The same tag is returning two different IDs on each OS. I believe the Android tag ID is correct and wrong on iOS. Interestingly, reversing the ID on iOS is similar, but not exactly, some values are swapped together.

I used the nfc-test-app to verify and the issue is present there too (I copied components react-native-nfc-manager/example/AppV2Iso15693, react-native-nfc-manager/example/AppV2Index, react-native-nfc-manager/example/AppV2 components and added console.log(tag))

method used on Android NfcManager.setEventListener(NfcEvents.DiscoverTag, tag=>tag)

method used on iOS await NfcManager.requestTechnology([NfcTech.Iso15693IOS]); const tag = await NfcManager.getTag();

[whitedogg13]

Hi @Megatron4537 Nice catch, thanks for reporting this!

I believe its something like endianness issue.

The tag id in native platform is reported as a byte array, and we simply convert it into a hex string one by one, then send back to JS layer. So the issue is because iOS and Android has their id array in reverse order when dealing with 15693 tag.

For example:

• in Android, the id is [0xAD, 0x3C, 0x11 0x7E, 0x00, 0x01, 0x04, 0xE0]
• in iOS, the id is [0xE0, 0x04, 0x01, 0x00, 0x7E, 0x11, 0x3C, 0xAD]

It might be an iOS platform bug, but I think it's safer to swap the byte order in your application code for now.

Thanks!

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