feat(firebase_messaging, iOS): add scene delegate support for firebase_messaging (#17888)

* feat(firebase_messaging): implement scene delegate support for iOS

* feat(firebase_messaging, iOS): add scene delegate support firebase_messaging

* chore: add missing newline at end of AppDelegate.h, AppDelegate.m, and Info.plist

Author: SelaseKay

packages/firebase_messaging/firebase_messaging/ios/firebase_messaging/Sources/firebase_messaging/FLTFirebaseMessagingPlugin.m

@@ -89,6 +89,11 @@ + (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar> *)registrar {
   [registrar addMethodCallDelegate:instance channel:channel];
 #if !TARGET_OS_OSX
   [registrar publish:instance];  // iOS only supported
+  if (@available(iOS 13.0, *)) {
+    if ([registrar respondsToSelector:@selector(addSceneDelegate:)]) {
+      [registrar performSelector:@selector(addSceneDelegate:) withObject:instance];
+    }
+  }
 #endif
 }
 
@@ -530,6 +535,30 @@ - (BOOL)application:(UIApplication *)application
 }  // didReceiveRemoteNotification
 #endif
 
+#pragma mark - SceneDelegate Methods
+
+#if !TARGET_OS_OSX
+- (BOOL)scene:(UIScene *)scene
+    willConnectToSession:(UISceneSession *)session
+                 options:(UISceneConnectionOptions *)connectionOptions {
+  // Handle launch notification if present
+  NSDictionary *remoteNotification =
+      connectionOptions.notificationResponse.notification.request.content.userInfo;
+  if (remoteNotification != nil) {
+    // If remoteNotification exists, it is the notification that opened the app.
+    _initialNotification =
+        [FLTFirebaseMessagingPlugin remoteMessageUserInfoToDict:remoteNotification];
+    _initialNotificationID = remoteNotification[@"gcm.message_id"];
+  }
+
+  // Register for remote notifications in scene delegate
+  // This is critical for getting APNS token when using UISceneDelegate
+  [[UIApplication sharedApplication] registerForRemoteNotifications];
+
+  return YES;
+}
+#endif
+
 #pragma mark - Firebase Messaging API
 
 - (void)messagingUnsubscribeFromTopic:(id)arguments

packages/firebase_messaging/firebase_messaging/ios/firebase_messaging/Sources/firebase_messaging/include/FLTFirebaseMessagingPlugin.h

@@ -29,6 +29,11 @@
 // Suppress warning - use can add the Flutter plugin for Firebase Analytics.
 #define FIREBASE_ANALYTICS_SUPPRESS_WARNING
 
+// Forward declaration for FlutterSceneLifeCycleDelegate if not available
+#if !TARGET_OS_OSX
+@protocol FlutterSceneLifeCycleDelegate;
+#endif
+
 #if TARGET_OS_OSX
 #ifdef __FF_NOTIFICATIONS_SUPPORTED_PLATFORM
 @interface FLTFirebaseMessagingPlugin : FLTFirebasePlugin <FlutterPlugin,
@@ -48,11 +53,21 @@ API_AVAILABLE(ios(10.0))
 @interface FLTFirebaseMessagingPlugin : FLTFirebasePlugin <FlutterPlugin,
                                                            FLTFirebasePlugin,
                                                            FIRMessagingDelegate,
-                                                           UIApplicationDelegate,
-                                                           UNUserNotificationCenterDelegate>
+                                                           UIApplicationDelegate
+#if __has_include(<Flutter/FlutterSceneLifeCycleDelegate.h>) || defined(FlutterSceneLifeCycleDelegate)
+                                                           ,
+                                                           FlutterSceneLifeCycleDelegate
+#endif
+                                                           >
 #else
-@interface FLTFirebaseMessagingPlugin
-    : FLTFirebasePlugin <FlutterPlugin, FLTFirebasePlugin, FIRMessagingDelegate>
+@interface FLTFirebaseMessagingPlugin : FLTFirebasePlugin <FlutterPlugin,
+                                                           FLTFirebasePlugin,
+                                                           FIRMessagingDelegate
+#if __has_include(<Flutter/FlutterSceneLifeCycleDelegate.h>) || defined(FlutterSceneLifeCycleDelegate)
+                                                           ,
+                                                           FlutterSceneLifeCycleDelegate
+#endif
+                                                           >
 #endif
 #endif
-@end
+@end