NFC World:

Apple will expand the iPhone’s NFC chip reading capabilities before the end of 2019 so that it can be used to read data stored in security chips like those used in passports, according to comments made by the UK government.

And:

The iPhone’s NFC functionality is currently restricted so that it is only able to read NDEF data, so the UK government has been unable to make its EU Exit app available to EU citizens with an iPhone.

The app is available currently on Android devices only.

And:

“I’m also pleased to confirm that Apple will make the identity document check app available on their devices by the end of the year,” says Home Secretary Sajid Javid.

NFC tag reading was added to Apple Watch and iOS with the release of iOS 11. This appears to be expanding the type of tags iOS can read so the UK government can use an iOS app to verify identities.