use_modular_headers (#42204)

diff --git a/examples/catalog/ios/Runner/AppDelegate.m b/examples/catalog/ios/Runner/AppDelegate.m
index d427758..109febb 100644
--- a/examples/catalog/ios/Runner/AppDelegate.m
+++ b/examples/catalog/ios/Runner/AppDelegate.m
@@ -1,5 +1,5 @@
-#include "AppDelegate.h"
-#include "GeneratedPluginRegistrant.h"
+#import "AppDelegate.h"
+#import "GeneratedPluginRegistrant.h"
 
 @implementation AppDelegate
 
diff --git a/examples/flutter_gallery/ios/Podfile b/examples/flutter_gallery/ios/Podfile
index e8ba04f..61291f1 100644
--- a/examples/flutter_gallery/ios/Podfile
+++ b/examples/flutter_gallery/ios/Podfile
@@ -27,6 +27,8 @@
 end
 
 target 'Runner' do
+  use_modular_headers!
+  
   # Flutter Pods
   pod 'Flutter', :path => ENV['FLUTTER_FRAMEWORK_DIR']
   
diff --git a/examples/flutter_gallery/ios/Runner/AppDelegate.m b/examples/flutter_gallery/ios/Runner/AppDelegate.m
index ef69bf5..39cdc5b 100644
--- a/examples/flutter_gallery/ios/Runner/AppDelegate.m
+++ b/examples/flutter_gallery/ios/Runner/AppDelegate.m
@@ -1,5 +1,5 @@
-#include "AppDelegate.h"
-#include "GeneratedPluginRegistrant.h"
+#import "AppDelegate.h"
+#import "GeneratedPluginRegistrant.h"
 
 @implementation AppDelegate
 
diff --git a/examples/flutter_view/ios/Podfile b/examples/flutter_view/ios/Podfile
index f29633f..827fe47 100644
--- a/examples/flutter_view/ios/Podfile
+++ b/examples/flutter_view/ios/Podfile
@@ -7,6 +7,7 @@
 target 'Runner' do
   # Uncomment this line if you're using Swift or would like to use dynamic frameworks
    use_frameworks!
+   use_modular_headers!
 
   # Pods for Runner
   pod 'MaterialControls', '~> 1.2.2'
diff --git a/examples/flutter_view/ios/Runner/AppDelegate.m b/examples/flutter_view/ios/Runner/AppDelegate.m
index c92e987..cd6c623 100644
--- a/examples/flutter_view/ios/Runner/AppDelegate.m
+++ b/examples/flutter_view/ios/Runner/AppDelegate.m
@@ -1,4 +1,4 @@
-#include "AppDelegate.h"
+#import "AppDelegate.h"
 #import <Flutter/Flutter.h>
 
 @implementation AppDelegate
diff --git a/examples/hello_world/ios/Runner/AppDelegate.m b/examples/hello_world/ios/Runner/AppDelegate.m
index b1a0c02..cafbf73 100644
--- a/examples/hello_world/ios/Runner/AppDelegate.m
+++ b/examples/hello_world/ios/Runner/AppDelegate.m
@@ -1,5 +1,5 @@
-#include "AppDelegate.h"
-#include "GeneratedPluginRegistrant.h"
+#import "AppDelegate.h"
+#import "GeneratedPluginRegistrant.h"
 
 @implementation AppDelegate
 
diff --git a/examples/hello_world/ios/Runner/GeneratedPluginRegistrant.h b/examples/hello_world/ios/Runner/GeneratedPluginRegistrant.h
index 3b700eb..ed9a5c6 100644
--- a/examples/hello_world/ios/Runner/GeneratedPluginRegistrant.h
+++ b/examples/hello_world/ios/Runner/GeneratedPluginRegistrant.h
@@ -7,8 +7,11 @@
 
 #import <Flutter/Flutter.h>
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface GeneratedPluginRegistrant : NSObject
 + (void)registerWithRegistry:(NSObject<FlutterPluginRegistry>*)registry;
 @end
 
+NS_ASSUME_NONNULL_END
 #endif /* GeneratedPluginRegistrant_h */
diff --git a/examples/image_list/ios/Runner/AppDelegate.m b/examples/image_list/ios/Runner/AppDelegate.m
index 59a72e9..70e8393 100644
--- a/examples/image_list/ios/Runner/AppDelegate.m
+++ b/examples/image_list/ios/Runner/AppDelegate.m
@@ -1,5 +1,5 @@
-#include "AppDelegate.h"
-#include "GeneratedPluginRegistrant.h"
+#import "AppDelegate.h"
+#import "GeneratedPluginRegistrant.h"
 
 @implementation AppDelegate
 
diff --git a/examples/layers/ios/Runner/AppDelegate.m b/examples/layers/ios/Runner/AppDelegate.m
index 74db37f..4270096 100644
--- a/examples/layers/ios/Runner/AppDelegate.m
+++ b/examples/layers/ios/Runner/AppDelegate.m
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "AppDelegate.h"
-#include "GeneratedPluginRegistrant.h"
+#import "AppDelegate.h"
+#import "GeneratedPluginRegistrant.h"
 
 @implementation AppDelegate
 
diff --git a/examples/platform_view/ios/Podfile b/examples/platform_view/ios/Podfile
index 0938daf..8c87860 100644
--- a/examples/platform_view/ios/Podfile
+++ b/examples/platform_view/ios/Podfile
@@ -27,6 +27,8 @@
 end
 
 target 'Runner' do
+  use_modular_headers!
+  
   # Prepare symlinks folder. We use symlinks to avoid having Podfile.lock
   # referring to absolute paths on developers' machines.
   system('rm -rf .symlinks')
diff --git a/examples/platform_view/ios/Runner/AppDelegate.m b/examples/platform_view/ios/Runner/AppDelegate.m
index 8088f13..48eae2c 100644
--- a/examples/platform_view/ios/Runner/AppDelegate.m
+++ b/examples/platform_view/ios/Runner/AppDelegate.m
@@ -2,9 +2,9 @@
 // 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.
 
-#include "AppDelegate.h"
-#include "GeneratedPluginRegistrant.h"
-#include "PlatformViewController.h"
+#import "AppDelegate.h"
+#import "GeneratedPluginRegistrant.h"
+#import "PlatformViewController.h"
 
 @implementation AppDelegate {
   FlutterResult _flutterResult;
diff --git a/examples/stocks/ios/Runner/AppDelegate.m b/examples/stocks/ios/Runner/AppDelegate.m
index 74db37f..4270096 100644
--- a/examples/stocks/ios/Runner/AppDelegate.m
+++ b/examples/stocks/ios/Runner/AppDelegate.m
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "AppDelegate.h"
-#include "GeneratedPluginRegistrant.h"
+#import "AppDelegate.h"
+#import "GeneratedPluginRegistrant.h"
 
 @implementation AppDelegate