Implement Combine support for Firebase

[peterfriese]

This is a tracking bug for adding Combine support to the Firebase SDKs for Apple's platforms.

If you're interested in contributing code by writing Combine Publishers for one of the SDKs listed below, please leave a comment so we can track interested (and pencil you in on the task list).

Related info

Please check out the following for details about this work stream:

• DECISIONS.md lists some of our decisions. Not set in stone (and we're always happy to discuss), but serves as a guiding principle
• DEVELOPING.md contains step-by-step instructions for setting up your development environment for working on Combine Publishers for Firebase
• README.md contains a description of Combine support for Firebase from a user's perspective. Consider adding a code snippet for the publishers you build to give users an impression of how to use them.
• CHANGELOG.md is the change log for this module

Roadmap

MVP

• Implement Combine support for the SDKs marked as P1
• Submit for API review
• Address any feedback
• Merge into the main branch
• Gather feedback from the wider community

Close the gap

• Begin work on supporting remaining SDKs
• API review for this work package
• Merge into main branch
• Gather feedback from the wider community

GA

• Review feedback from the community
• Address any requests for changes
• Launch 🚀

SDKs to support

Finished

In Progress

• [P1] Authentication (see Implement Combine support for Firebase Auth #7296)
• [P1] Cloud Firestore (see Add Combine support to Firestore #6960, Combine support for Decodable QuerySnapshot publisher #7549)
• [P2] Realtime Database (see WIP: RTDB Swift Combine #7544)
• [P1] Cloud Functions (see Combine Support: Cloud Functions #7547)
• [P2] Cloud Storage (@ziadtamim)

Backlog

Interested in helping out? Leave a comment so we can pencil you in.

• [P3] Machine Learning
• [P3] Cloud Messaging
• [P3] Remote Config
• [P3] Dynamic Links

[ziadtamim]

@peterfriese I will support Cloud Storage.

[peterfriese]

@peterfriese I will support Cloud Storage.

Great - thanks, Ziad. I penciled you in - once you send a draft PR, I will add the PR to our project tracker.

[paulb777]

@peterfriese Should we close and open separate issue for specific items?

[peterfriese]

Yes, we should do that. I'll spend some time next week to clean up the tracker and set up new issues.

[mortenbekditlevsen]

I still have a PR for initial Combine support in FirebaseDatabase. Let me know if that's of any use:

#7544

[ziadtamim]

There is a PR for Decodable QuerySnapshot publisher #7549