Add AsyncStream support for Remote Config #15352

peterfriese · 2025-09-22T21:28:04Z

This PR introduces a new configUpdates property to RemoteConfig, providing an AsyncThrowingStream for consuming real-time config updates. This offers a modern, Swift Concurrency-native alternative to the existing closure-based listener, making it easier to integrate real-time updates into async/await workflows.

Motivation

The existing addOnConfigUpdateListener uses a closure-based callback, which can be cumbersome in modern Swift applications that have adopted Swift Concurrency. By providing an AsyncThrowingStream, we offer a more ergonomic and idiomatic way for developers to receive real-time updates, simplifying their code and improving readability.

Implementation Details

FirebaseRemoteConfig/Swift/RemoteConfig+Async.swift: A new file containing an extension on RemoteConfig.
- It adds a public configUpdates property that returns an AsyncThrowingStream<RemoteConfigUpdate, Error>.
- The stream's implementation wraps the existing addOnConfigUpdateListener.
- The listener's lifecycle is automatically managed: it is added when iteration begins and removed when the stream is terminated (e.g., through cancellation).
FirebaseRemoteConfig/Tests/Swift/SwiftAPI/AsyncStreamTests.swift: A new test suite for the async stream functionality.
- Includes mock objects to simulate the real-time service and listener registration.
- Contains tests for various scenarios, including successful updates, error handling, stream cancellation, and handling of multiple updates.

Example usage

Developers can now listen for real-time updates using a simple for try await loop:

func listenForRealtimeUpdates() {
  Task {
    do {
      for try await configUpdate in remoteConfig.configUpdates {
        print("Updated keys: \(configUpdate.updatedKeys)")

        // Activate the new config to make it available
        let status = try await remoteConfig.activate()
        print("Config activated with status: \(status)")
      }
    } catch {
      print("Error listening for remote config updates: \(error)")
    }
  }
}

This change is purely additive and does not affect any existing APIs.

paulb777

LGTM - thanks @peterfriese !

Leaving approval to @ncooke3 or the RC team

FirebaseRemoteConfig/CHANGELOG.md

docs/AsyncStreams/api-design-proposal.md

FirebaseRemoteConfig/CHANGELOG.md

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>

docs/AsyncStreams/api-design-proposal.md

FirebaseRemoteConfig/Tests/Swift/SwiftAPI/AsyncStreamTests.swift

…the naming scheme

ncooke3 · 2025-10-02T14:28:47Z

Closing and re-opening to trigger all CI checks again.

FirebaseRemoteConfig/Swift/RemoteConfig+Async.swift

FirebaseRemoteConfig/Tests/Swift/SwiftAPI/AsyncSequenceTests.swift

FirebaseRemoteConfig/Swift/RemoteConfig+Async.swift

FirebaseRemoteConfig/CHANGELOG.md

ncooke3

Left some suggestions to fix current CI errors. Also suggesting to change doc comment and changelog to prefer sequence over stream (impl. detail).

ncooke3 · 2025-10-02T23:25:42Z

Down to one linting failure (unit test flake?). Rerunning:

      - NOTE  | [iOS] xcodebuild:  2025-10-02 22:29:13.149516+0000 AppHost-FirebaseRemoteConfig-Unit-Tests[92144:368595] [[FirebaseRemoteConfig]] 12.4.0 - [FirebaseRemoteConfig][I-RCN000073] Failed to get installations token. Error : Error Domain=com.firebase.installations Code=0 "The server responded with an error:

ncooke3 · 2025-10-03T13:36:48Z

Down to one linting failure (unit test flake?). Rerunning:

      - NOTE  | [iOS] xcodebuild:  2025-10-02 22:29:13.149516+0000 AppHost-FirebaseRemoteConfig-Unit-Tests[92144:368595] [[FirebaseRemoteConfig]] 12.4.0 - [FirebaseRemoteConfig][I-RCN000073] Failed to get installations token. Error : Error Domain=com.firebase.installations Code=0 "The server responded with an error:

Perhaps not a flake. Going to see how to surface which test this is coming from.

ncooke3 · 2025-10-03T14:17:13Z

I haven't been able to reproduce:

    Testing started
 -> FirebaseRemoteConfig (12.4.0)
    - NOTE  | xcodebuild:  note: Using codesigning identity override: -
    - NOTE  | xcodebuild:  note: Building targets in dependency order
    - NOTE  | [iOS] xcodebuild:  note: Target dependency graph (18 targets)
    - NOTE  | xcodebuild:  note: Metadata extraction skipped. No AppIntents.framework dependency found. (in target 'FirebaseSharedSwift' from project 'Pods')
    - NOTE  | xcodebuild:  note: Metadata extraction skipped. No AppIntents.framework dependency found. (in target 'FirebaseRemoteConfigInterop' from project 'Pods')
    - NOTE  | xcodebuild:  note: Metadata extraction skipped. No AppIntents.framework dependency found. (in target 'FirebaseCoreInternal' from project 'Pods')
    - NOTE  | xcodebuild:  note: Metadata extraction skipped. No AppIntents.framework dependency found. (in target 'FirebaseRemoteConfig' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Signing static framework with --generate-pre-encrypt-hashes (in target 'Pods-App' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Metadata extraction skipped. No AppIntents.framework dependency found. (in target 'App' from project 'App')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'App' from project 'App')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'Pods-App' from project 'Pods')
    - NOTE  | xcodebuild:  Pods.xcodeproj: warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 9.0, but the range of supported deployment target versions is 12.0 to 18.2.99. (in target 'PromisesObjC' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'PromisesObjC' from project 'Pods')
    - NOTE  | xcodebuild:  Pods.xcodeproj: warning: The iOS Simulator deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 9.0, but the range of supported deployment target versions is 12.0 to 18.2.99. (in target 'PromisesObjC-FBLPromises_Privacy' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'PromisesObjC-FBLPromises_Privacy' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'GoogleUtilities-GoogleUtilities_Privacy' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'GoogleUtilities' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseSharedSwift' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseRemoteConfigInterop' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseRemoteConfig-FirebaseRemoteConfig_Privacy' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseRemoteConfig' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseInstallations-FirebaseInstallations_Privacy' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseInstallations' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseCoreInternal-FirebaseCoreInternal_Privacy' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseCoreInternal' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseCore-FirebaseCore_Privacy' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseCore' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseABTesting-FirebaseABTesting_Privacy' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Disabling previews because SWIFT_VERSION is set and SWIFT_OPTIMIZATION_LEVEL=-O, expected -Onone (in target 'FirebaseABTesting' from project 'Pods')
    - NOTE  | xcodebuild:  note: Target dependency graph (19 targets)
    - NOTE  | xcodebuild:  note: Using stub executor library without Swift entry point. (in target 'AppHost-FirebaseRemoteConfig-Unit-Tests' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Metadata extraction skipped. No AppIntents.framework dependency found. (in target 'FirebaseRemoteConfig-Unit-unit' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  The server responded with an error: 
    - NOTE  | [iOS] xcodebuild:  2025-10-03 10:15:06.050224-0400 AppHost-FirebaseRemoteConfig-Unit-Tests[52071:8570339] [[FirebaseRemoteConfig]] 12.4.0 - [FirebaseRemoteConfig][I-RCN000073] Failed to get installations token. Error : Error Domain=com.firebase.installations Code=0 "The server responded with an error: 
    - NOTE  | [iOS] xcodebuild:  " UserInfo={NSLocalizedFailureReason=The server responded with an error: 
    - NOTE  | [iOS] xcodebuild:  note: Metadata extraction skipped. No AppIntents.framework dependency found. (in target 'FirebaseRemoteConfig-Unit-swift-api-tests' from project 'Pods')
    - NOTE  | [iOS] xcodebuild:  note: Metadata extraction skipped. No AppIntents.framework dependency found. (in target 'FirebaseRemoteConfig-Unit-fake-console-tests' from project 'Pods')

FirebaseRemoteConfig passed validation.
nickcooke@nickcooke-mac2 firebase (peterfriese/asyncsequences/remoteconfig) % xcode-select -p
/Applications/Xcode_16.2.app/Contents/Developer

ncooke3 · 2025-10-03T14:37:55Z

Should be OK to ignore, I verified that the new test suite you added is running and passing.

peterfriese added 6 commits September 22, 2025 19:46

Add design document

5cd140b

Cleanup

8a6390c

Initial implementation of AsyncStream for RC + basic test

45b8a27

Add more complete unit tests

75f2daf

Formatting

b15e24a

Fix copyright and add Sendable conformance

fdd1aae

peterfriese self-assigned this Sep 22, 2025

peterfriese added the api: remoteconfig label Sep 22, 2025

peterfriese linked an issue Sep 22, 2025 that may be closed by this pull request

Implement AsyncStream support for Remote Config #15351

Open

peterfriese requested review from ncooke3 and paulb777 September 22, 2025 21:49

peterfriese marked this pull request as ready for review September 22, 2025 21:52

Add changelog entry

2487abe

paulb777 reviewed Sep 23, 2025

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ncooke3 reviewed Sep 23, 2025

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peterfriese and others added 3 commits September 24, 2025 15:55

Update FirebaseRemoteConfig/CHANGELOG.md

17548a7

Co-authored-by: Nick Cooke <36927374+ncooke3@users.noreply.github.com>

Fix typo

b99276d

Fix conflicting API in API design proposal for Cloud Storage

a963b69

peterfriese requested review from ncooke3 and paulb777 September 24, 2025 14:29

ncooke3 reviewed Sep 24, 2025

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peterfriese added 3 commits September 25, 2025 08:28

Simplify listener attachment syncronisation

8b8bdbc

Fix styling

bc822c0

Remove design doc in favour of adding it via a separate PR

e1088fe

paulb777 approved these changes Sep 29, 2025

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peterfriese added 3 commits September 30, 2025 11:49

Rename stream from updates to configUpdates to better align with …

32c8034

…the naming scheme

Return stream as an AsyncSequence

12c08c0

Update tests

39133d6

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Add AsyncStream support for Remote Config #15352

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Motivation

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Example usage

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