refactor(firestore,apple): migrate iOS/macOS plugin implementation to Swift

packages/cloud_firestore/cloud_firestore/ios/cloud_firestore.podspec

@@ -24,10 +24,10 @@ Pod::Spec.new do |s|
   s.license          = { :file => '../LICENSE' }
   s.authors          = 'The Chromium Authors'
   s.source           = { :path => '.' }
-  s.source_files     = 'cloud_firestore/Sources/cloud_firestore/**/*.{h,m,mm}'
-  s.public_header_files = 'cloud_firestore/Sources/cloud_firestore/include/Public/**/*.h'
-  s.private_header_files = 'cloud_firestore/Sources/cloud_firestore/include/Private/**/*.h'
+  s.source_files     = 'cloud_firestore/Sources/**/*.{swift,h,m,mm}'
+  s.public_header_files = 'cloud_firestore/Sources/cloud_firestore_objc/include/*.h'
 
+  s.swift_version = '5.0'
   s.ios.deployment_target = '15.0'
   s.dependency 'Flutter'
 
@@ -36,7 +36,6 @@ Pod::Spec.new do |s|
 
   s.static_framework = true
   s.pod_target_xcconfig = {
-    'GCC_PREPROCESSOR_DEFINITIONS' => "LIBRARY_VERSION=\\\"#{library_version}\\\" LIBRARY_NAME=\\\"flutter-fire-fst\\\"",
     'DEFINES_MODULE' => 'YES'
   }
 end

packages/cloud_firestore/cloud_firestore/ios/cloud_firestore/Package.swift

@@ -24,22 +24,30 @@ let package = Package(
     .package(name: "FlutterFramework", path: "../FlutterFramework"),
   ],
   targets: [
+    // SPM does not allow mixing Swift and ObjC in a single target.
+    .target(
+      name: "cloud_firestore_objc",
+      dependencies: [
+        .product(name: "FirebaseFirestore", package: "firebase-ios-sdk")
+      ],
+      path: "Sources/cloud_firestore_objc",
+      publicHeadersPath: "include",
+      cSettings: [
+        .headerSearchPath("include")
+      ]
+    ),
     .target(
       name: "cloud_firestore",
       dependencies: [
+        "cloud_firestore_objc",
         .product(name: "FirebaseFirestore", package: "firebase-ios-sdk"),
         .product(name: "firebase-core", package: "firebase_core"),
         .product(name: "FlutterFramework", package: "FlutterFramework"),
       ],
+      path: "Sources/cloud_firestore",
       resources: [
         .process("Resources")
-      ],
-      cSettings: [
-        .headerSearchPath("include/cloud_firestore/Private"),
-        .headerSearchPath("include/cloud_firestore/Public"),
-        .define("LIBRARY_VERSION", to: "\"\(libraryVersion)\""),
-        .define("LIBRARY_NAME", to: "\"flutter-fire-fst\""),
       ]
-    )
+    ),
   ]
 )

packages/cloud_firestore/cloud_firestore/ios/cloud_firestore/Sources/cloud_firestore/Constants.swift

@@ -0,0 +1,19 @@
+// Copyright 2021 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// Auto-generated file. Do not edit.
+public let versionNumber = "6.8.0"
+
+let kFLTFirebaseFirestoreChannelName = "plugins.flutter.io/firebase_firestore"
+let kFLTFirebaseFirestoreQuerySnapshotEventChannelName =
+  "plugins.flutter.io/firebase_firestore/query"
+let kFLTFirebaseFirestoreDocumentSnapshotEventChannelName =
+  "plugins.flutter.io/firebase_firestore/document"
+let kFLTFirebaseFirestoreSnapshotsInSyncEventChannelName =
+  "plugins.flutter.io/firebase_firestore/snapshotsInSync"
+let kFLTFirebaseFirestoreTransactionChannelName =
+  "plugins.flutter.io/firebase_firestore/transaction"
+let kFLTFirebaseFirestoreLoadBundleChannelName =
+  "plugins.flutter.io/firebase_firestore/loadBundle"
+let kFirebaseFirestoreLibraryName = "flutter-fire-fst"

packages/cloud_firestore/cloud_firestore/ios/cloud_firestore/Sources/cloud_firestore/DocumentSnapshotStreamHandler.swift

@@ -0,0 +1,81 @@
+// Copyright 2021 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import FirebaseFirestore
+import Foundation
+
+#if canImport(firebase_core)
+  import firebase_core
+#else
+  import firebase_core_shared
+#endif
+
+#if os(iOS)
+  import Flutter
+#elseif os(macOS)
+  import FlutterMacOS
+#endif
+
+final class DocumentSnapshotStreamHandler: NSObject, FlutterStreamHandler {
+  private let firestore: Firestore
+  private let reference: DocumentReference
+  private let includeMetadataChanges: Bool
+  private let serverTimestampBehavior: FirebaseFirestore.ServerTimestampBehavior
+  private let source: FirebaseFirestore.ListenSource
+  private var listenerRegistration: ListenerRegistration?
+
+  init(
+    firestore: Firestore,
+    reference: DocumentReference,
+    includeMetadataChanges: Bool,
+    serverTimestampBehavior: FirebaseFirestore.ServerTimestampBehavior,
+    source: FirebaseFirestore.ListenSource
+  ) {
+    self.firestore = firestore
+    self.reference = reference
+    self.includeMetadataChanges = includeMetadataChanges
+    self.serverTimestampBehavior = serverTimestampBehavior
+    self.source = source
+  }
+
+  func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink)
+    -> FlutterError?
+  {
+    let options = SnapshotListenOptions()
+      .withIncludeMetadataChanges(includeMetadataChanges)
+      .withSource(source)
+
+    listenerRegistration = reference.addSnapshotListener(options: options) {
+      [serverTimestampBehavior] snapshot, error in
+      if let error {
+        let (code, message) = FirebaseFirestoreUtils.errorCodeAndMessage(from: error)
+        DispatchQueue.main.async {
+          events(
+            FLTFirebasePlugin.createFlutterError(
+              fromCode: code,
+              message: message,
+              optionalDetails: ["code": code, "message": message],
+              andOptionalNSError: error as NSError
+            )
+          )
+        }
+      } else if let snapshot {
+        DispatchQueue.main.async {
+          events(
+            PigeonParser.toPigeonDocumentSnapshot(
+              snapshot, serverTimestampBehavior: serverTimestampBehavior
+            )
+          )
+        }
+      }
+    }
+    return nil
+  }
+
+  func onCancel(withArguments arguments: Any?) -> FlutterError? {
+    listenerRegistration?.remove()
+    listenerRegistration = nil
+    return nil
+  }
+}