android - What actually happens when persistence is enabled in Firebase?

Question

When turning on persistence for Firebase in iOS what actually happens to my observers and how they behave on a technical level?

I have a good idea how it should work on a high-level based on this https://firebase.google.com/docs/database/ios/offline-capabilities - Firebase essentially keeps a cached copy of the data you can access whilst offline.

What I don't understand is how many times my observers should fire and with what information.

• Does firebase always trigger my observers once with any cached data first (or null if there isn't any data) followed by the server data.
• Or does it only send the cached data if it exists followed by the server data.
• Is there any difference between observerSingleValue and a continous observer's behaviour when in persistence mode ?

In our app with persistence enabled, I have noticed:

• Firebase just sending the server data
• Firebase sending the cached data if it exists then the server data.
• Firebase sending the cached data and null if it doesn't exist followed by the server data.

It would be good to clear this up so we know which should be the normal behaviour :)

Answer 1

Waitting for answers