Migrate standard sample apps to UIScene lifecycle (#2884)

Fixes https://github.com/flutter/flutter/issues/176957

platform_view_swift/ios/Runner/AppDelegate.swift

@@ -2,42 +2,56 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import UIKit
 import Flutter
+import UIKit
 
-@UIApplicationMain
-@objc class AppDelegate: FlutterAppDelegate, PlatformViewControllerDelegate {
+@main
+@objc class AppDelegate: FlutterAppDelegate, FlutterImplicitEngineDelegate, PlatformViewControllerDelegate {
   var flutterResult: FlutterResult?
 
   override func application(
     _ application: UIApplication,
     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
   ) -> Bool {
-    GeneratedPluginRegistrant.register(with: self)
-        let controller: FlutterViewController = window?.rootViewController as! FlutterViewController
-        let channel = FlutterMethodChannel.init(name: "dev.flutter.sample/platform_view_swift", binaryMessenger: controller.binaryMessenger)
-        
-        channel.setMethodCallHandler({
-            (call: FlutterMethodCall, result: @escaping FlutterResult) -> Void in
-            if ("switchView" == call.method) {
-                self.flutterResult = result
-                
-                let platformViewController = PlatformViewController(nibName: "PlatformViewController", bundle: nil)
-                platformViewController.counter = call.arguments as! Int
-                platformViewController.delegate = self
-                
-                let navigationController = UINavigationController(rootViewController: platformViewController)
-                navigationController.navigationBar.topItem?.title = "Platform View"
-                controller.present(navigationController, animated: true, completion: nil)
-            } else {
-                result(FlutterMethodNotImplemented)
-            }
-        });
-        
     return super.application(application, didFinishLaunchingWithOptions: launchOptions)
   }
-    
-    func didUpdateCounter(counter: Int) {
-        flutterResult?(counter)
-    }
+
+  func didInitializeImplicitFlutterEngine(_ engineBridge: FlutterImplicitEngineBridge) {
+    GeneratedPluginRegistrant.register(with: engineBridge.pluginRegistry)
+
+    let registrar = engineBridge.pluginRegistry.registrar(forPlugin: "PlatformViewSwift")
+    let channel = FlutterMethodChannel(
+      name: "dev.flutter.sample/platform_view_swift",
+      binaryMessenger: engineBridge.applicationRegistrar.messenger()
+    )
+
+    channel.setMethodCallHandler({
+      [weak self] (call: FlutterMethodCall, result: @escaping FlutterResult) -> Void in
+      guard let self = self else { return }
+      if "switchView" == call.method {
+        self.flutterResult = result
+
+        let platformViewController = PlatformViewController(nibName: "PlatformViewController", bundle: nil)
+        platformViewController.counter = call.arguments as! Int
+        platformViewController.delegate = self
+
+        let navigationController = UINavigationController(rootViewController: platformViewController)
+        navigationController.navigationBar.topItem?.title = "Platform View"
+
+        let presenter = registrar?.viewController ?? UIApplication.shared.connectedScenes
+          .compactMap { $0 as? UIWindowScene }
+          .flatMap { $0.windows }
+          .first { $0.isKeyWindow }?
+          .rootViewController
+
+        presenter?.present(navigationController, animated: true, completion: nil)
+      } else {
+        result(FlutterMethodNotImplemented)
+      }
+    })
+  }
+
+  func didUpdateCounter(counter: Int) {
+    flutterResult?(counter)
+  }
 }

platform_view_swift/ios/Runner/Info.plist

@@ -22,6 +22,27 @@
 	<string>$(FLUTTER_BUILD_NUMBER)</string>
 	<key>LSRequiresIPhoneOS</key>
 	<true/>
+	<key>UIApplicationSceneManifest</key>
+	<dict>
+		<key>UIApplicationSupportsMultipleScenes</key>
+		<false/>
+		<key>UISceneConfigurations</key>
+		<dict>
+			<key>UIWindowSceneSessionRoleApplication</key>
+			<array>
+				<dict>
+					<key>UISceneClassName</key>
+					<string>UIWindowScene</string>
+					<key>UISceneConfigurationName</key>
+					<string>flutter</string>
+					<key>UISceneDelegateClassName</key>
+					<string>FlutterSceneDelegate</string>
+					<key>UISceneStoryboardFile</key>
+					<string>Main</string>
+				</dict>
+			</array>
+		</dict>
+	</dict>
 	<key>UILaunchStoryboardName</key>
 	<string>LaunchScreen</string>
 	<key>UIMainStoryboardFile</key>
@@ -41,5 +62,9 @@
 	</array>
 	<key>UIViewControllerBasedStatusBarAppearance</key>
 	<false/>
+	<key>CADisableMinimumFrameDurationOnPhone</key>
+	<true/>
+	<key>UIApplicationSupportsIndirectInputEvents</key>
+	<true/>
 </dict>
 </plist>