[Config] Merge RemoteConfig and its Swift extension in a non-breaking way (#11720)

Author: ncooke3

FirebaseRemoteConfig.podspec

@@ -40,13 +40,15 @@ app update.
     'FirebaseABTesting/Sources/Private/*.h',
     'FirebaseCore/Extension/*.h',
     'FirebaseInstallations/Source/Library/Private/*.h',
+    'FirebaseRemoteConfigSwift/Sources/**/*.swift',
   ]
   s.public_header_files = base_dir + 'Public/FirebaseRemoteConfig/*.h'
   s.pod_target_xcconfig = {
     'GCC_C_LANGUAGE_STANDARD' => 'c99',
     'HEADER_SEARCH_PATHS' => '"${PODS_TARGET_SRCROOT}"'
   }
   s.dependency 'FirebaseABTesting', '~> 10.0'
+  s.dependency 'FirebaseSharedSwift', '~> 10.0'
   s.dependency 'FirebaseCore', '~> 10.0'
   s.dependency 'FirebaseInstallations', '~> 10.0'
   s.dependency 'GoogleUtilities/Environment', '~> 7.8'

FirebaseRemoteConfigSwift.podspec

@@ -35,11 +35,10 @@ app update.
   s.prefix_header_file      = false
 
   s.source_files = [
-    'FirebaseRemoteConfigSwift/Sources/**/*.swift',
+    'FirebaseRemoteConfigSwift/Exporter/**/*.swift',
   ]
 
   s.dependency 'FirebaseRemoteConfig', '~> 10.0'
-  s.dependency 'FirebaseSharedSwift', '~> 10.0'
 
   # Run Swift API tests on a real backend.
   s.test_spec 'swift-api-tests' do |swift_api|

FirebaseRemoteConfigSwift/Exporter/Exporter.swift

@@ -0,0 +1,20 @@
+// Copyright 2023 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.
+
+// TODO(ncooke3): Add warning that importing this extension is deprecated.
+
+// The `@_exported` is needed to prevent breaking clients that are using
+// types prefixed with the `FirebaseRemoteConfigSwift` module name (e.g.
+// `FirebaseRemoteConfigSwift.RemoteConfigValueCodableError`).
+@_exported import FirebaseRemoteConfig

FirebaseRemoteConfigSwift/Sources/Codable.swift

@@ -15,9 +15,26 @@
  */
 
 import Foundation
-import FirebaseRemoteConfig
+#if SWIFT_PACKAGE
+  @_exported import FirebaseRemoteConfigInternal
+#endif // SWIFT_PACKAGE
 import FirebaseSharedSwift
 
+#if SWIFT_PACKAGE
+  // This is a trick to force generate a `FirebaseRemoteConfig-Swift.h` header
+  // that re-exports `FirebaseRemoteConfigInternal` for Objective-C clients. It
+  // is important for the below code to reference a Remote Config symbol defined
+  // in Objective-C as that will import the symbol's module
+  // (`FirebaseRemoteConfigInternal`) in the generated header. This allows
+  // Objective-C clients to import Remote Config's Objective-C API using
+  // `@import FirebaseRemoteConfig;`. This API is not needed for Swift clients
+  // and is therefore hidden for them for the foreseeable future.
+  @available(iOS 100, *)
+  @objc public extension RemoteConfig {
+    var __do_not_call: String { "" }
+  }
+#endif // SWIFT_PACKAGE
+
 public enum RemoteConfigValueCodableError: Error {
   case unsupportedType(String)
 }

FirebaseRemoteConfigSwift/Sources/FirebaseRemoteConfigValueDecoderHelper.swift

@@ -15,7 +15,9 @@
  */
 
 import Foundation
-import FirebaseRemoteConfig
+#if SWIFT_PACKAGE
+  @_exported import FirebaseRemoteConfigInternal
+#endif // SWIFT_PACKAGE
 import FirebaseSharedSwift
 
 /// Implement the FirebaseRemoteConfigValueDecoding protocol for the shared Firebase decoder to

FirebaseRemoteConfigSwift/Sources/PropertyWrapper/RemoteConfigProperty.swift

@@ -14,7 +14,10 @@
  * limitations under the License.
  */
 
-import FirebaseRemoteConfig
+#if SWIFT_PACKAGE
+  @_exported import FirebaseRemoteConfigInternal
+#endif // SWIFT_PACKAGE
+
 import SwiftUI
 
 /// A property wrapper that listens to a Remote Config value.

FirebaseRemoteConfigSwift/Sources/PropertyWrapper/RemoteConfigValueObservable.swift

@@ -14,7 +14,9 @@
  * limitations under the License.
  */
 
-import FirebaseRemoteConfig
+#if SWIFT_PACKAGE
+  @_exported import FirebaseRemoteConfigInternal
+#endif // SWIFT_PACKAGE
 import FirebaseCore
 import SwiftUI
 

FirebaseRemoteConfigSwift/Sources/Value.swift

@@ -15,7 +15,9 @@
  */
 
 import Foundation
-import FirebaseRemoteConfig
+#if SWIFT_PACKAGE
+  @_exported import FirebaseRemoteConfigInternal
+#endif // SWIFT_PACKAGE
 
 /// Implements subscript overloads to enable Remote Config values to be accessed
 /// in a type-safe way directly from the current config.

FirebaseRemoteConfigSwift/Tests/SwiftAPI/Codable.swift

@@ -13,7 +13,6 @@
 // limitations under the License.
 
 import FirebaseRemoteConfig
-import FirebaseRemoteConfigSwift
 
 import XCTest
 

FirebaseRemoteConfigSwift/Tests/SwiftAPI/PropertyWrapperDefaultConfigsTests.swift

@@ -16,7 +16,7 @@
 
 import FirebaseCore
 import FirebaseRemoteConfig
-import FirebaseRemoteConfigSwift
+
 import XCTest
 
 let ConfigKeyForThisTestOnly = "PropertyWrapperDefaultConfigsTestsKey"