Flutter FireStore offline access to sub collections [closed]

Question

I'm was working with flutter and fireStore as a database. Everything is working fine, but when I tried to offline access to sub collections I couldn't.

I think I did something wrong, because there is just 1 question about this Stack Overflow and the answer wasn't clear to me. I tried adding this line to my code

firebaseFirestore.settings = const Settings( cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED, persistenceEnabled: true,
    );

and

mealsSnapshots = await mealsDoc.get(GetOptions(source: Source.cache))

but nothing changed

I'm looking for someone have experience in firebase help me, Thank you for your time