fix(ios): center TextInput typed text when lineHeight > fontSize on Fabric

Port the Paper-only fix from facebook#38359 to the Fabric path. When
lineHeight > fontSize on iOS, UIKit anchors glyphs to the bottom of
the attributed-string line box, making typed text render visually too
low.

The RCTApplyBaselineOffset helper already ships in Fabric (used by
<Text> in RCTTextLayoutManager) but was never wired into the
<TextInput> path. Call it inside
RCTTextInputComponentView._setAttributedString:.

To avoid an extra mutableCopy on every programmatic text update, also
widen RCTNSAttributedStringFromAttributedString[Box] to return
NSMutableAttributedString *. The Value-mode path already built a
mutable and returned it typed as immutable; the OpaquePointer-mode
path now mutableCopy's explicitly.

Tracked by facebook#39145.

Author: janicduplessis

packages/react-native/React/Fabric/Mounting/ComponentViews/TextInput/RCTTextInputComponentView.mm

@@ -575,8 +575,8 @@ - (void)setTextAndSelection:(NSInteger)eventCount
   }
   _comingFromJS = YES;
   if (value && ![value isEqualToString:_backedTextInputView.attributedText.string]) {
-    NSAttributedString *attributedString =
-        [[NSAttributedString alloc] initWithString:value attributes:_backedTextInputView.defaultTextAttributes];
+    NSMutableAttributedString *attributedString =
+        [[NSMutableAttributedString alloc] initWithString:value attributes:_backedTextInputView.defaultTextAttributes];
     [self _setAttributedString:attributedString];
     [self _updateState];
   }
@@ -766,8 +766,10 @@ - (void)_restoreTextSelectionAndIgnoreCaretChange:(BOOL)ignore
   [_backedTextInputView setSelectedTextRange:range notifyDelegate:YES];
 }
 
-- (void)_setAttributedString:(NSAttributedString *)attributedString
+- (void)_setAttributedString:(NSMutableAttributedString *)attributedString
 {
+  RCTApplyBaselineOffset(attributedString);
+
   if ([self _textOf:attributedString equals:_backedTextInputView.attributedText]) {
     return;
   }

packages/react-native/ReactCommon/react/renderer/textlayoutmanager/platform/ios/react/renderer/textlayoutmanager/RCTAttributedTextUtils.h

@@ -28,10 +28,10 @@ NSMutableDictionary<NSAttributedStringKey, id> *RCTNSTextAttributesFromTextAttri
 /*
  * Conversions amond `NSAttributedString`, `AttributedString` and `AttributedStringBox`.
  */
-NSAttributedString *RCTNSAttributedStringFromAttributedString(
+NSMutableAttributedString *RCTNSAttributedStringFromAttributedString(
     const facebook::react::AttributedString &attributedString);
 
-NSAttributedString *RCTNSAttributedStringFromAttributedStringBox(
+NSMutableAttributedString *RCTNSAttributedStringFromAttributedStringBox(
     const facebook::react::AttributedStringBox &attributedStringBox);
 
 facebook::react::AttributedStringBox RCTAttributedStringBoxFromNSAttributedString(

packages/react-native/ReactCommon/react/renderer/textlayoutmanager/platform/ios/react/renderer/textlayoutmanager/RCTAttributedTextUtils.mm

@@ -405,7 +405,7 @@ void RCTApplyBaselineOffset(NSMutableAttributedString *attributedText)
   return nsAttributedStringFragment;
 }
 
-NSAttributedString *RCTNSAttributedStringFromAttributedString(const AttributedString &attributedString)
+NSMutableAttributedString *RCTNSAttributedStringFromAttributedString(const AttributedString &attributedString)
 {
   static UIImage *placeholderImage;
   static dispatch_once_t onceToken;
@@ -428,13 +428,13 @@ void RCTApplyBaselineOffset(NSMutableAttributedString *attributedText)
   return nsAttributedString;
 }
 
-NSAttributedString *RCTNSAttributedStringFromAttributedStringBox(const AttributedStringBox &attributedStringBox)
+NSMutableAttributedString *RCTNSAttributedStringFromAttributedStringBox(const AttributedStringBox &attributedStringBox)
 {
   switch (attributedStringBox.getMode()) {
     case AttributedStringBox::Mode::Value:
       return RCTNSAttributedStringFromAttributedString(attributedStringBox.getValue());
     case AttributedStringBox::Mode::OpaquePointer:
-      return (NSAttributedString *)unwrapManagedObject(attributedStringBox.getOpaquePointer());
+      return [(NSAttributedString *)unwrapManagedObject(attributedStringBox.getOpaquePointer()) mutableCopy];
   }
 }