Add Swift Package Manager Support (closes #80)

wakelock_plus/ios/wakelock_plus.podspec

@@ -13,12 +13,12 @@ Plugin that allows you to keep the device screen awake, i.e. prevent the screen
   s.license          = { :file => '../LICENSE' }
   s.author           = { 'Flutter Team' => 'flutter-dev@googlegroups.com' }
   s.source           = { :path => '.' }
-  s.source_files = 'Classes/**/*'
-  s.public_header_files = 'Classes/**/*.h'
+  s.source_files = 'wakelock_plus/Sources/wakelock_plus/**/*.{h,m}'
+  s.public_header_files = 'wakelock_plus/Sources/wakelock_plus/include/**/*.h'
   s.dependency 'Flutter'
   s.platform = :ios, '11.0'
 
   # Flutter.framework does not contain a i386 slice.
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386' }
-  s.resource_bundles = {'wakelock_plus_privacy' => ['Resources/PrivacyInfo.xcprivacy']}
+  s.resource_bundles = {'wakelock_plus_privacy' => ['wakelock_plus/Sources/wakelock_plus/Resources/PrivacyInfo.xcprivacy']}
 end

wakelock_plus/ios/wakelock_plus/Package.swift

@@ -0,0 +1,27 @@
+// swift-tools-version: 5.9
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "wakelock_plus",
+    platforms: [
+        .iOS("11.0")
+    ],
+    products: [
+        .library(name: "wakelock-plus", targets: ["wakelock_plus"])
+    ],
+    dependencies: [],
+    targets: [
+        .target(
+            name: "wakelock_plus",
+            dependencies: [],
+            resources: [
+                .process("Resources")
+            ],
+            cSettings: [
+                .headerSearchPath("include/wakelock_plus")
+            ]
+        )
+    ]
+)

wakelock_plus/ios/Classes/messages.g.m → wakelock_plus/ios/wakelock_plus/Sources/wakelock_plus/messages.g.m

@@ -1,7 +1,7 @@
 // Autogenerated from Pigeon (v22.7.0), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
-#import "messages.g.h"
+#import "./include/wakelock_plus/messages.g.h"
 
 #if TARGET_OS_OSX
 #import <FlutterMacOS/FlutterMacOS.h>

wakelock_plus/pigeons/messages.dart

@@ -13,10 +13,12 @@ class IsEnabledMessage {
 @ConfigurePigeon(PigeonOptions(
   dartOut: '../wakelock_plus_platform_interface/lib/messages.g.dart',
   dartTestOut: '../wakelock_plus_platform_interface/test/messages.g.dart',
-  objcHeaderOut: 'ios/Classes/messages.g.h',
-  objcSourceOut: 'ios/Classes/messages.g.m',
+  objcHeaderOut:
+      'ios/wakelock_plus/Sources/wakelock_plus/include/wakelock_plus/messages.g.h',
+  objcSourceOut: 'ios/wakelock_plus/Sources/wakelock_plus/messages.g.m',
   objcOptions: ObjcOptions(
     prefix: 'WAKELOCKPLUS',
+    headerIncludePath: './include/wakelock_plus/messages.g.h',
   ),
   kotlinOptions: KotlinOptions(errorClassName: "WakelockPlusFlutterError"),
   kotlinOut: