[iOS] Send connectionClosed message when resignFirstResponder to ensure framework focus state is correct.

shell/platform/darwin/ios/framework/Source/FlutterEngine.mm

@@ -1095,7 +1095,14 @@ - (void)flutterTextInputView:(FlutterTextInputView*)textInputView
                               arguments:@[ @(client) ]];
 }
 
-- (void)flutterTextInputViewDidResignFirstResponder:(FlutterTextInputView*)textInputView {
+- (void)flutterTextInputView:(FlutterTextInputView*)textInputView
+    didResignFirstResponderWithTextInputClient:(int)client {
+  // When flutter text input view resign first responder, send a message to
+  // framework to ensure the focus state is correct. This is useful when close
+  // keyboard from platform side.
+  [_textInputChannel.get() invokeMethod:@"TextInputClient.onConnectionClosed"
+                              arguments:@[ @(client) ]];
+
   // Platform view's first responder detection logic:
   //
   // All text input widgets (e.g. EditableText) are backed by a dummy UITextInput view

shell/platform/darwin/ios/framework/Source/FlutterEngineTest.mm

@@ -13,9 +13,14 @@
 #import "flutter/shell/platform/darwin/ios/framework/Source/FlutterBinaryMessengerRelay.h"
 #import "flutter/shell/platform/darwin/ios/framework/Source/FlutterDartProject_Internal.h"
 #import "flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine_Test.h"
+#import "flutter/shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.h"
 
 FLUTTER_ASSERT_ARC
 
+@interface FlutterEngine () <FlutterTextInputDelegate>
+
+@end
+
 @interface FlutterEngineTest : XCTestCase
 @end
 
@@ -313,4 +318,17 @@ - (void)testCanEnableDisableEmbedderAPIThroughInfoPlist {
   }
 }
 
+- (void)testFlutterTextInputViewDidResignFirstResponderWillCallTextInputClientConnectionClosed {
+  id mockBinaryMessenger = OCMClassMock([FlutterBinaryMessengerRelay class]);
+  FlutterEngine* engine = [[FlutterEngine alloc] init];
+  [engine setBinaryMessenger:mockBinaryMessenger];
+  [engine runWithEntrypoint:FlutterDefaultDartEntrypoint initialRoute:@"test"];
+  [engine flutterTextInputView:nil didResignFirstResponderWithTextInputClient:1];
+  FlutterMethodCall* methodCall =
+      [FlutterMethodCall methodCallWithMethodName:@"TextInputClient.onConnectionClosed"
+                                        arguments:@[ @(1) ]];
+  NSData* encodedMethodCall = [[FlutterJSONMethodCodec sharedInstance] encodeMethodCall:methodCall];
+  OCMVerify([mockBinaryMessenger sendOnChannel:@"flutter/textinput" message:encodedMethodCall]);
+}
+
 @end

shell/platform/darwin/ios/framework/Source/FlutterTextInputDelegate.h

@@ -59,8 +59,8 @@ typedef NS_ENUM(NSInteger, FlutterFloatingCursorDragState) {
     insertTextPlaceholderWithSize:(CGSize)size
                        withClient:(int)client;
 - (void)flutterTextInputView:(FlutterTextInputView*)textInputView removeTextPlaceholder:(int)client;
-- (void)flutterTextInputViewDidResignFirstResponder:(FlutterTextInputView*)textInputView;
-
+- (void)flutterTextInputView:(FlutterTextInputView*)textInputView
+    didResignFirstResponderWithTextInputClient:(int)client;
 @end
 
 #endif  // SHELL_PLATFORM_IOS_FRAMEWORK_SOURCE_FLUTTERTEXTINPUTDELEGATE_H_

shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.mm

@@ -1043,7 +1043,8 @@ - (BOOL)canBecomeFirstResponder {
 - (BOOL)resignFirstResponder {
   BOOL success = [super resignFirstResponder];
   if (success) {
-    [self.textInputDelegate flutterTextInputViewDidResignFirstResponder:self];
+    [self.textInputDelegate flutterTextInputView:self
+        didResignFirstResponderWithTextInputClient:_textInputClient];
   }
   return success;
 }