1. Apply this patch: https://gist.github.com/marcinwasowicz/7f04bd592dd4a800adbc96b720e200b7. It creates js code to subscribe for auth metadata events and sends this event from C++ upon each draft update (contents of the event are just dummy strings).
2. Build iOS app.
3. Ensure that each time you write one letter you can see `console.log` with dummy auth metadata in `native yarn dev` terminal.