hide FlutterTextInputView from accessibility

Author: yjbanov

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

@@ -517,8 +517,28 @@ - (void)deleteBackward {
 
 @end
 
+/**
+ * Hides `FlutterTextInputView` from iOS accessibility system so it
+ * does not show up twice, once where it is in the `UIView` hierarchy,
+ * and a second time as part of the `SemanticsObject` hierarchy.
+ */
+@interface FlutterTextInputViewAccessibilityHider : UIView {
+}
+
+@end
+
+@implementation FlutterTextInputViewAccessibilityHider {
+}
+
+- (BOOL)accessibilityElementsHidden {
+  return YES;
+}
+
+@end
+
 @implementation FlutterTextInputPlugin {
   FlutterTextInputView* _view;
+  FlutterTextInputViewAccessibilityHider* _inputHider;
 }
 
 @synthesize textInputDelegate = _textInputDelegate;
@@ -528,6 +548,7 @@ - (instancetype)init {
 
   if (self) {
     _view = [[FlutterTextInputView alloc] init];
+    _inputHider = [[FlutterTextInputViewAccessibilityHider alloc] init];
   }
 
   return self;
@@ -536,6 +557,7 @@ - (instancetype)init {
 - (void)dealloc {
   [self hideTextInput];
   [_view release];
+  [_inputHider release];
 
   [super dealloc];
 }
@@ -572,13 +594,15 @@ - (void)showTextInput {
            @"The application must have a key window since the keyboard client "
            @"must be part of the responder chain to function");
   _view.textInputDelegate = _textInputDelegate;
-  [[UIApplication sharedApplication].keyWindow addSubview:_view];
+  [_inputHider addSubview:_view];
+  [[UIApplication sharedApplication].keyWindow addSubview:_inputHider];
   [_view becomeFirstResponder];
 }
 
 - (void)hideTextInput {
   [_view resignFirstResponder];
   [_view removeFromSuperview];
+  [_inputHider removeFromSuperview];
 }
 
 - (void)setTextInputClient:(int)client withConfiguration:(NSDictionary*)configuration {