C# Xamarin IOS Backgrounding Loop with HTML Request

Question

I am looking for a way to do a html request in the background every 120minutes

The Plan is:

1. Request on HTML Site save the Response (HTML String local on the phone)

2. Do it again 120min later (Intervall can be different)

3. Compare the strings if anything has changed send a local notification

Anybody knows a good way ? Is that possible?

Snippets would be great.

Thank you for your time and help. Greetings