[iOS] Add iOS live text input engine side support

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

@@ -17,7 +17,7 @@
 constexpr char kTextPlainFormat[] = "text/plain";
 const UInt32 kKeyPressClickSoundId = 1306;
 
-}  // namespaces
+}  // namespace
 
 namespace flutter {
 
@@ -37,6 +37,8 @@
 
 @implementation FlutterPlatformPlugin {
   fml::WeakPtr<FlutterEngine> _engine;
+  // Used to detect whether this device has live text input ability or not.
+  UITextField* _textField;
 }
 
 - (instancetype)initWithEngine:(fml::WeakPtr<FlutterEngine>)engine {
@@ -88,6 +90,8 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
     result(nil);
   } else if ([method isEqualToString:@"Clipboard.hasStrings"]) {
     result([self clipboardHasStrings]);
+  } else if ([method isEqualToString:@"LiveText.isLiveTextInputAvailable"]) {
+    result(@([self isLiveTextInputAvailable]));
   } else {
     result(FlutterMethodNotImplemented);
   }
@@ -287,4 +291,19 @@ - (NSDictionary*)clipboardHasStrings {
   return @{@"value" : @(hasStrings)};
 }
 
+- (BOOL)isLiveTextInputAvailable {
+  return [[self textField] canPerformAction:@selector(captureTextFromCamera:) withSender:nil];
+}
+
+- (UITextField*)textField {
+  if (_textField == nil) {
+    _textField = [[UITextField alloc] init];
+  }
+  return _textField;
+}
+
+- (void)dealloc {
+  [_textField release];
+  [super dealloc];
+}
 @end

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

@@ -14,6 +14,10 @@
 @interface FlutterPlatformPluginTest : XCTestCase
 @end
 
+@interface FlutterPlatformPlugin ()
+- (BOOL)isLiveTextInputAvailable;
+@end
+
 @implementation FlutterPlatformPluginTest
 
 - (void)testClipboardHasCorrectStrings {
@@ -111,4 +115,24 @@ - (void)testPopSystemNavigator {
   OCMVerify([navigationControllerMock popViewControllerAnimated:YES]);
 }
 
+- (void)testWhetherDeviceHasLiveTextInputInvokeCorrectly {
+  FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"test" project:nil];
+  std::unique_ptr<fml::WeakPtrFactory<FlutterEngine>> _weakFactory =
+      std::make_unique<fml::WeakPtrFactory<FlutterEngine>>(engine);
+  XCTestExpectation* invokeExpectation =
+      [self expectationWithDescription:@"isLiveTextInputAvailableInvoke"];
+  FlutterPlatformPlugin* plugin =
+      [[FlutterPlatformPlugin alloc] initWithEngine:_weakFactory->GetWeakPtr()];
+  FlutterPlatformPlugin* mockPlugin = OCMPartialMock(plugin);
+  FlutterMethodCall* methodCall =
+      [FlutterMethodCall methodCallWithMethodName:@"LiveText.isLiveTextInputAvailable"
+                                        arguments:nil];
+  FlutterResult result = ^(id result) {
+    OCMVerify([mockPlugin isLiveTextInputAvailable]);
+    [invokeExpectation fulfill];
+  };
+  [mockPlugin handleMethodCall:methodCall result:result];
+  [self waitForExpectationsWithTimeout:1 handler:nil];
+}
+
 @end

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

@@ -49,6 +49,7 @@
 static NSString* const kSetMarkedTextRectMethod = @"TextInput.setMarkedTextRect";
 static NSString* const kFinishAutofillContextMethod = @"TextInput.finishAutofillContext";
 static NSString* const kSetSelectionRectsMethod = @"TextInput.setSelectionRects";
+static NSString* const kStartLiveTextInputMethod = @"TextInput.startLiveTextInput";
 
 #pragma mark - TextInputConfiguration Field Names
 static NSString* const kSecureTextEntry = @"obscureText";
@@ -2120,6 +2121,9 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
   } else if ([method isEqualToString:kSetSelectionRectsMethod]) {
     [self setSelectionRects:args];
     result(nil);
+  } else if ([method isEqualToString:kStartLiveTextInputMethod]) {
+    [self startLiveTextInput];
+    result(nil);
   } else {
     result(FlutterMethodNotImplemented);
   }
@@ -2164,6 +2168,15 @@ - (void)setSelectionRects:(NSArray*)rects {
   _activeView.selectionRects = rectsAsRect;
 }
 
+- (void)startLiveTextInput {
+  if (@available(iOS 15.0, *)) {
+    if (_activeView == nil || !_activeView.isFirstResponder) {
+      return;
+    }
+    [_activeView captureTextFromCamera:nil];
+  }
+}
+
 - (void)showTextInput {
   _activeView.viewResponder = _viewResponder;
   [self addToInputParentViewIfNeeded:_activeView];

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

@@ -68,6 +68,7 @@ - (void)cleanUpViewHierarchy:(BOOL)includeActiveView
 - (UIView*)hostView;
 - (fml::WeakPtr<FlutterTextInputPlugin>)getWeakPtr;
 - (void)addToInputParentViewIfNeeded:(FlutterTextInputView*)inputView;
+- (void)startLiveTextInput;
 @end
 
 @interface FlutterTextInputPluginTest : XCTestCase
@@ -165,6 +166,17 @@ - (FlutterTextRange*)getLineRangeFromTokenizer:(id<UITextInputTokenizer>)tokeniz
 }
 
 #pragma mark - Tests
+
+- (void)testInvokeStartLiveTextInput {
+  FlutterMethodCall* methodCall =
+      [FlutterMethodCall methodCallWithMethodName:@"TextInput.startLiveTextInput" arguments:nil];
+  FlutterTextInputPlugin* mockPlugin = OCMPartialMock(textInputPlugin);
+  [mockPlugin handleMethodCall:methodCall
+                        result:^(id _Nullable result){
+                        }];
+  OCMVerify([mockPlugin startLiveTextInput]);
+}
+
 - (void)testNoDanglingEnginePointer {
   __weak FlutterTextInputPlugin* weakFlutterTextInputPlugin;
   FlutterViewController* flutterViewController = [[FlutterViewController alloc] init];