[ios] Fix hold and drag spacebar does not move cursor when obscureText is true. (#40216)

Fixes [flutter/flutter#122139](flutter/flutter#122139) with flutter pr [flutter/flutter#122383](flutter/flutter#122383)

Author: LinXunFeng

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

@@ -56,6 +56,7 @@
 static NSString* const kDeprecatedSetSelectionRectsMethod = @"TextInput.setSelectionRects";
 static NSString* const kSetSelectionRectsMethod = @"Scribble.setSelectionRects";
 static NSString* const kStartLiveTextInputMethod = @"TextInput.startLiveTextInput";
+static NSString* const kUpdateConfigMethod = @"TextInput.updateConfig";
 
 #pragma mark - TextInputConfiguration Field Names
 static NSString* const kSecureTextEntry = @"obscureText";
@@ -2124,6 +2125,9 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
   } else if ([method isEqualToString:kStartLiveTextInputMethod]) {
     [self startLiveTextInput];
     result(nil);
+  } else if ([method isEqualToString:kUpdateConfigMethod]) {
+    [self updateConfig:args];
+    result(nil);
   } else {
     result(FlutterMethodNotImplemented);
   }
@@ -2463,6 +2467,23 @@ - (void)clearTextInputClient {
   _activeView.frame = CGRectZero;
 }
 
+- (void)updateConfig:(NSDictionary*)dictionary {
+  BOOL isSecureTextEntry = [dictionary[kSecureTextEntry] boolValue];
+  for (UIView* view in self.textInputViews) {
+    if ([view isKindOfClass:[FlutterTextInputView class]]) {
+      FlutterTextInputView* inputView = (FlutterTextInputView*)view;
+      // The feature of holding and draging spacebar to move cursor is affected by
+      // secureTextEntry, so when obscureText is updated, we need to update secureTextEntry
+      // and call reloadInputViews.
+      // https://github.com/flutter/flutter/issues/122139
+      if (inputView.isSecureTextEntry != isSecureTextEntry) {
+        inputView.secureTextEntry = isSecureTextEntry;
+        [inputView reloadInputViews];
+      }
+    }
+  }
+}
+
 #pragma mark UIIndirectScribbleInteractionDelegate
 
 - (BOOL)indirectScribbleInteraction:(UIIndirectScribbleInteraction*)interaction

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

@@ -164,6 +164,14 @@ - (FlutterTextRange*)getLineRangeFromTokenizer:(id<UITextInputTokenizer>)tokeniz
   return (FlutterTextRange*)range;
 }
 
+- (void)updateConfig:(NSDictionary*)config {
+  FlutterMethodCall* updateConfigCall =
+      [FlutterMethodCall methodCallWithMethodName:@"TextInput.updateConfig" arguments:config];
+  [textInputPlugin handleMethodCall:updateConfigCall
+                             result:^(id _Nullable result){
+                             }];
+}
+
 #pragma mark - Tests
 
 - (void)testWillNotCrashWhenViewControllerIsNil {
@@ -647,6 +655,29 @@ - (void)testPropagatePressEventsToViewController2 {
                                              withEvent:[OCMArg isNotNil]]);
 }
 
+- (void)testUpdateSecureTextEntry {
+  NSDictionary* config = self.mutableTemplateCopy;
+  [config setValue:@"YES" forKey:@"obscureText"];
+  [self setClientId:123 configuration:config];
+
+  NSArray<FlutterTextInputView*>* inputFields = self.installedInputViews;
+  FlutterTextInputView* inputView = OCMPartialMock(inputFields[0]);
+
+  __block int callCount = 0;
+  OCMStub([inputView reloadInputViews]).andDo(^(NSInvocation* invocation) {
+    callCount++;
+  });
+
+  XCTAssertTrue(inputView.isSecureTextEntry);
+
+  config = self.mutableTemplateCopy;
+  [config setValue:@"NO" forKey:@"obscureText"];
+  [self updateConfig:config];
+
+  XCTAssertEqual(callCount, 1);
+  XCTAssertFalse(inputView.isSecureTextEntry);
+}
+
 #pragma mark - TextEditingDelta tests
 - (void)testTextEditingDeltasAreGeneratedOnTextInput {
   FlutterTextInputView* inputView = [[FlutterTextInputView alloc] initWithOwner:textInputPlugin];