How to look at a json in an off application and send notification if any value has more than zero?

I’m trying to create an app that, although it is off, check if a JSON that I have in an API returns me more than zero in any of its values.
If so, how could you send a notification to the mobile with that information.
What should I use? Local notifications? Background mode? Notifications Push?

Is there an example that I can follow? I’m kind of lost.

Thank you