How to set associated domains for NFC background reading in iOS12

Question

I'm trying to set up my NFC Reader app to support the new background reading feature in iOS12:

https://developer.apple.com/documentation/corenfc/adding_support_for_background_tag_reading?changes=latest_minor

But I'm really struggling with the associated domains part.

Next, enter the domain for each universal link supported by your app.

I tried adding the associated domain in different formats. For example:

mailto
mailto:

But I'm always getting this error from AppStoreConnect:

App Store Connect Operation Error ERROR ITMS-90046: "Invalid Code Signing Entitlements. Your application bundle's signature contains code signing entitlements that are not supported on iOS. Specifically, value 'mailto' for key 'com.apple.developer.associated-domains' in 'Payload/NFC Reader.app/NFC Reader' is not supported."

How do I set those associated domains correctly?

Answer 1

Your associated domains should be websites, not "mailto" or something similar.