allow custom attributedTextWithBaseTextAttributes in RCTBaseTextShado…

…wView subclasses (#25283)

Summary:
This is similar to #24995 but for iOS.
Motivation: when building a custom Text or TextInput (eg with rich text support), one needs custom text processing logic (turning the JS text value to a `NSAttributedString`).

RCTBaseTextShadowView contains `- (NSAttributedString *)attributedTextWithBaseTextAttributes:(nullable RCTTextAttributes *)baseTextAttributes;`

https://github.com/facebook/react-native/blob/853c667eb5a66612c33e0786ab6c458dcaee6133/Libraries/Text/BaseText/RCTBaseTextShadowView.m#L78

This method, given `self.reactSubviews` creates and returns an instance of [NSMutableAttributedString](https://developer.apple.com/documentation/foundation/nsmutableattributedstring?language=objc). It's currently possible to override this method in subclasses, but the original implementation reads and writes two cache fields which are private. This PR just changes the access modifiers so that subclasses of `RCTBaseTextShadowView` can also access the caching fields.

## Changelog

Not needed I guess.
Pull Request resolved: #25283

Test Plan: This will work just the same - works locally, CI should pass.

Differential Revision: D15873741

Pulled By: cpojer

fbshipit-source-id: dd26a4241f2ac6c0870b6c302939e2f3b0ecc8ff

Libraries/Text/BaseText/RCTBaseTextShadowView.h

@@ -13,7 +13,10 @@ NS_ASSUME_NONNULL_BEGIN
 
 extern NSString *const RCTBaseTextShadowViewEmbeddedShadowViewAttributeName;
 
-@interface RCTBaseTextShadowView : RCTShadowView
+@interface RCTBaseTextShadowView : RCTShadowView {
+  @protected NSAttributedString *_Nullable cachedAttributedText;
+  @protected RCTTextAttributes *_Nullable cachedTextAttributes;
+}
 
 @property (nonatomic, strong) RCTTextAttributes *textAttributes;
 

Libraries/Text/BaseText/RCTBaseTextShadowView.m

@@ -29,10 +29,6 @@ static void RCTInlineViewYogaNodeDirtied(YGNodeRef node)
 }
 
 @implementation RCTBaseTextShadowView
-{
-  NSAttributedString *_Nullable _cachedAttributedText;
-  RCTTextAttributes *_Nullable _cachedTextAttributes;
-}
 
 - (instancetype)init
 {
@@ -86,8 +82,8 @@ - (NSAttributedString *)attributedTextWithBaseTextAttributes:(nullable RCTTextAt
     textAttributes = [self.textAttributes copy];
   }
 
-  if (_cachedAttributedText && [_cachedTextAttributes isEqual:textAttributes]) {
-    return _cachedAttributedText;
+  if (cachedAttributedText && [cachedTextAttributes isEqual:textAttributes]) {
+    return cachedAttributedText;
   }
 
   NSMutableAttributedString *attributedText = [NSMutableAttributedString new];
@@ -133,17 +129,17 @@ - (NSAttributedString *)attributedTextWithBaseTextAttributes:(nullable RCTTextAt
 
   [self clearLayout];
 
-  _cachedAttributedText = [attributedText copy];
-  _cachedTextAttributes = textAttributes;
+  cachedAttributedText = [attributedText copy];
+  cachedTextAttributes = textAttributes;
 
-  return _cachedAttributedText;
+  return cachedAttributedText;
 }
 
 - (void)dirtyLayout
 {
   [super dirtyLayout];
-  _cachedAttributedText = nil;
-  _cachedTextAttributes = nil;
+  cachedAttributedText = nil;
+  cachedTextAttributes = nil;
 }
 
 - (void)didUpdateReactSubviews