Implement AsyncStream to listen for remote config updates

FirebaseRemoteConfig/Swift/RemoteConfig+AsyncStream.swift

@@ -0,0 +1,32 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+public extension RemoteConfig {
+  /// Asynchronous stream of configuration updates.
+  @available(iOS 13.0, macOS 10.15, macCatalyst 13.0, watchOS 7.0, tvOS 13.0, *)
+  var updateStream: AsyncStream<Result<RemoteConfigUpdate, Error>> {
+    AsyncStream { continuation in
+      let registration = self.addOnConfigUpdateListener { update, error in
+        if let error = error {
+          continuation.yield(.failure(error))
+        } else if let update {
+          continuation.yield(.success(update))
+        }
+      }
+      continuation.onTermination = { _ in
+        registration.remove()
+      }
+    }
+  }
+}