Firestore instance has already been started and its settings can no longer be changed.

[bobby-white]

I am trying to use Firestore natively with Obj-C, and with React Native.

I have a background process (which can be running while app is in foreground too) that I had to write natively, which periodically writes data to a collection in Firestore.
I also read data from Firestore in Javascript.

Both of these features work independently, but the read only happens in certain scenarios.

When I try to use firestore natively and in Javascript at the same time, I get the issue stating that:
Firestore instance has already been started and its settings can no longer be changed.

Is there any workarounds to this?

In Obj-c I am accessing Firestore using the Firebase SDKs directly, as follows:

// AppDelegate.m
#import <Firebase.h>
...
if ([FIRApp defaultApp] == nil) {
  [FIRApp configure];
}

// BackgroundTask.m
#import <Firebase.h>
...
[[[[FIRFirestore firestore] collectionWithPath:collectionPath] documentWithPath:documentPath] setData:data];

[bobby-white]

Is this an appropriate solution? Seems to work...

#import <RNFBFirestore/RNFBFirestoreCommon.h>
...

self.firestore = [RNFBFirestoreCommon getFirestoreForApp:[FIRApp defaultApp]];
...
[[[self.firestore collectionWithPath:collectionPath] documentWithPath:documentPath] setData:data];

Am I likely to run into any gotchas later down the road using this solution?

[mikehardy]

That's the correct solution I think, it's similar to where I was trying to go with my counsel in #4889 - basically, @react-native-firebase/firestore expects to be in charge of the firestore native configuration because we take config variables from firestore.json and may configure things based on that or allow overrides etc, so (re-)using the react-native-firebase init code in that way (by calling getFirestoreForApp allows all that to happen and then @react-native-firebase/firestore is satisfied when you go to use it at the JS level

The only thing I could think of as a trap is that you may not have the opportunity to change firestore pre-usage config settings unless you're careful with order of operations and where you do the configuration. Not a show-stopper by any means, just something to think about