[local_auth_darwin] Adds Swift Package Manager compatibility (flutter#6708)

Adds Swift Package Manager support to `local_auth_darwin`.

This does not migrate the example app's Xcode project to use Swift Package Manager, that's tracked by flutter#148021.

Fixes flutter#146911

Author: loic-sharma

packages/local_auth/local_auth_darwin/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.3.0
+
+* Adds Swift Package Manager compatibility.
+
 ## 1.2.2
 
 * Adds compatibility with `intl` 0.19.0.

packages/local_auth/local_auth_darwin/darwin/Assets/.gitkeep

@@ -14,11 +14,10 @@ Downloaded by pub (not CocoaPods).
   s.author           = { 'Flutter Dev Team' => 'flutter-dev@googlegroups.com' }
   s.source           = { :http => 'https://github.com/flutter/packages/tree/main/packages/local_auth' }
   s.documentation_url = 'https://pub.dev/packages/local_auth_darwin'
-  s.source_files = 'Classes/**/*'
-  s.public_header_files = 'Classes/**/*.h'
+  s.source_files = 'local_auth_darwin/Sources/local_auth_darwin/**/*.{h,m}'
+  s.public_header_files = 'local_auth_darwin/Sources/local_auth_darwin/include/**/*.h'
   s.dependency 'Flutter'
   s.platform = :ios, '12.0'
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES' }
-  s.resource_bundles = {'local_auth_darwin_privacy' => ['Resources/PrivacyInfo.xcprivacy']}
+  s.resource_bundles = {'local_auth_darwin_privacy' => ['local_auth_darwin/Sources/local_auth_darwin/Resources/PrivacyInfo.xcprivacy']}
 end
-

packages/local_auth/local_auth_darwin/darwin/local_auth_darwin.podspec

@@ -0,0 +1,32 @@
+// swift-tools-version: 5.9
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+// Copyright 2013 The Flutter 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 PackageDescription
+
+let package = Package(
+  name: "local_auth_darwin",
+  platforms: [
+    .iOS("12.0"),
+    .macOS("10.14"),
+  ],
+  products: [
+    .library(name: "local-auth-darwin", targets: ["local_auth_darwin"])
+  ],
+  dependencies: [],
+  targets: [
+    .target(
+      name: "local_auth_darwin",
+      dependencies: [],
+      resources: [
+        .process("Resources")
+      ],
+      cSettings: [
+        .headerSearchPath("include/local_auth_darwin")
+      ]
+    )
+  ]
+)

packages/local_auth/local_auth_darwin/darwin/local_auth_darwin/Package.swift

@@ -1,8 +1,8 @@
 // Copyright 2013 The Flutter 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 "FLALocalAuthPlugin.h"
-#import "FLALocalAuthPlugin_Test.h"
+#import "./include/local_auth_darwin/FLALocalAuthPlugin.h"
+#import "./include/local_auth_darwin/FLALocalAuthPlugin_Test.h"
 
 #import <LocalAuthentication/LocalAuthentication.h>
 

packages/local_auth/local_auth_darwin/darwin/Classes/FLALocalAuthPlugin.m renamed to packages/local_auth/local_auth_darwin/darwin/local_auth_darwin/Sources/local_auth_darwin/FLALocalAuthPlugin.m

@@ -4,7 +4,9 @@
 // Autogenerated from Pigeon (v13.1.2), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
-#import "messages.g.h"
+// The line below is manually edited. See:
+// https://github.com/flutter/flutter/issues/147587
+#import "./include/local_auth_darwin/messages.g.h"
 
 #if TARGET_OS_OSX
 #import <FlutterMacOS/FlutterMacOS.h>