[shared_preferences] Merge iOS and macOS implementations (flutter#6920)

This merges `shared_preferences_ios` and `shared_preferences_macos` into a new `shared_preferences_foundations` that replaces both of those packages, as described in flutter/flutter#117941:
- Renames `shared_preferences_macos` to `shared_prefrences_foundation`, since the macOS implementation is the Swift implementation, which is what we want to use going forward.
- Moves the implementation files to a shared directory (called `darwin/` in anticipation of flutter/flutter#115337), adjusting the code and podspec slightly to make it iOS-compatible
- Adds iOS support to the example, via `flutter create`-ing a new iOS example and wiring it up to use the existing native unit test. (This was done instead of moving the example from `shared_preferences_ios` since it seemed better to have the example be in Swift as well now.)
- Removes `shared_preferences_ios`.

Once this lands and has been published, a follow-up will update `shared_preferences` to use this new package instead of the other two, and the old ones will be marked as deprecated on pub.dev.

Part of flutter/flutter#117941

Author: stuartmorgan-g

CODEOWNERS

@@ -51,7 +51,7 @@ packages/ios_platform_images/ios/**                      @jmagman
 packages/local_auth/local_auth_ios/**                    @hellohuanlin
 packages/path_provider/path_provider_ios/**              @jmagman
 packages/quick_actions/quick_actions_ios/**              @hellohuanlin
-packages/shared_preferences/shared_preferences_ios/**    @cyanglaz
+packages/shared_preferences/shared_preferences_foundation/**  @cyanglaz
 packages/url_launcher/url_launcher_ios/**                @jmagman
 packages/video_player/video_player_avfoundation/**       @hellohuanlin
 packages/webview_flutter/webview_flutter_wkwebview/**    @cyanglaz
@@ -65,7 +65,6 @@ packages/url_launcher/url_launcher_linux/**              @cbracken
 # - macOS
 packages/file_selector/file_selector_macos/**            @cbracken
 packages/path_provider/path_provider_macos/**            @cbracken
-packages/shared_preferences/shared_preferences_macos/**  @cbracken
 packages/url_launcher/url_launcher_macos/**              @cbracken
 
 # - Windows

packages/shared_preferences/shared_preferences_ios/AUTHORS renamed to packages/shared_preferences/shared_preferences_foundation/AUTHORS

@@ -0,0 +1,5 @@
+## 2.1.0
+
+* Renames the package previously published as
+  [`shared_preferences_macos`](https://pub.dev/packages/shared_preferences_macos)
+* Adds iOS support.

packages/shared_preferences/shared_preferences_foundation/CHANGELOG.md

@@ -1,6 +1,6 @@
-# shared\_preferences\_ios
+# shared\_preferences\_foundation
 
-The iOS implementation of [`shared_preferences`][1].
+The iOS and macOS implementation of [`shared_preferences`][1].
 
 ## Usage
 

packages/shared_preferences/shared_preferences_ios/LICENSE renamed to packages/shared_preferences/shared_preferences_foundation/LICENSE

@@ -2,13 +2,24 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import FlutterMacOS
 import Foundation
 
+#if os(iOS)
+import Flutter
+#elseif os(macOS)
+import FlutterMacOS
+#endif
+
 public class SharedPreferencesPlugin: NSObject, FlutterPlugin, UserDefaultsApi {
   public static func register(with registrar: FlutterPluginRegistrar) {
     let instance = SharedPreferencesPlugin()
-    UserDefaultsApiSetup.setUp(binaryMessenger: registrar.messenger, api: instance)
+    // Workaround for https://github.com/flutter/flutter/issues/118103.
+#if os(iOS)
+    let messenger = registrar.messenger()
+#else
+    let messenger = registrar.messenger
+#endif
+    UserDefaultsApiSetup.setUp(binaryMessenger: messenger, api: instance)
   }
 
   func getAll() -> [String? : Any?] {

packages/shared_preferences/shared_preferences_ios/README.md renamed to packages/shared_preferences/shared_preferences_foundation/README.md

@@ -2,9 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import FlutterMacOS
 import XCTest
-@testable import shared_preferences_macos
+
+#if os(iOS)
+import Flutter
+#elseif os(macOS)
+import FlutterMacOS
+#endif
+
+@testable import shared_preferences_foundation
 
 class RunnerTests: XCTestCase {
   func testSetAndGet() throws {

packages/shared_preferences/shared_preferences_macos/macos/Classes/SharedPreferencesPlugin.swift renamed to packages/shared_preferences/shared_preferences_foundation/darwin/Classes/SharedPreferencesPlugin.swift

@@ -2,22 +2,22 @@
 # To learn more about a Podspec see http://guides.cocoapods.org/syntax/podspec.html
 #
 Pod::Spec.new do |s|
-  s.name             = 'shared_preferences_macos'
+  s.name             = 'shared_preferences_foundation'
   s.version          = '0.0.1'
-  s.summary          = 'macOS implementation of the shared_preferences plugin.'
+  s.summary          = 'iOS and macOS implementation of the shared_preferences plugin.'
   s.description      = <<-DESC
 Wraps NSUserDefaults, providing a persistent store for simple key-value pairs.
                        DESC
-  s.homepage         = 'https://github.com/flutter/plugins/tree/main/packages/shared_preferences/shared_preferences_macos'
+  s.homepage         = 'https://github.com/flutter/plugins/tree/main/packages/shared_preferences/shared_preferences_foundation'
   s.license          = { :type => 'BSD', :file => '../LICENSE' }
   s.author           = { 'Flutter Team' => '[email protected]' }
-  s.source           = { :http => 'https://github.com/flutter/plugins/tree/main/packages/shared_preferences/shared_preferences_macos' }
+  s.source           = { :http => 'https://github.com/flutter/plugins/tree/main/packages/shared_preferences/shared_preferences_foundation' }
   s.source_files = 'Classes/**/*'
-  s.dependency 'FlutterMacOS'
-
-  s.platform = :osx, '10.11'
+  s.ios.dependency 'Flutter'
+  s.osx.dependency 'FlutterMacOS'
+  s.ios.deployment_target = '9.0'
+  s.osx.deployment_target = '10.11'
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES' }
   s.swift_version = '5.0'
 
 end
-

packages/shared_preferences/shared_preferences_macos/macos/Classes/messages.g.swift renamed to packages/shared_preferences/shared_preferences_foundation/darwin/Classes/messages.g.swift

@@ -8,6 +8,7 @@
 .buildlog/
 .history
 .svn/
+migrate_working_dir/
 
 # IntelliJ related
 *.iml
@@ -31,9 +32,6 @@
 .pub/
 /build/
 
-# Web related
-lib/generated_plugin_registrant.dart
-
 # Symbolication related
 app.*.symbols