Build the framework for RCTParagraphComponentAccessibilityProvider

Summary:
Changelog:
[iOS][Added] - This is the first step to build RCTParagraphComponentAccessibilityProvider.  The main idea of RCTParagraphComponentAccessibilityProvider is to provide an array of accessible elements for the AttributedString in PCTParagraphComponentView.

Reviewed By: sammy-SC

Differential Revision: D22214855

fbshipit-source-id: 69d47555e86452620f89a4b2e21ed6065c8e669c

React/Fabric/Mounting/ComponentViews/Text/RCTParagraphComponentAccessibilityProvider.h

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+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <UIKit/UIKit.h>
+
+#import <react/attributedstring/AttributedString.h>
+
+#import "RCTParagraphComponentView.h"
+
+@interface RCTParagraphComponentAccessibilityProvider : NSObject
+
+- (instancetype)initWithString:(facebook::react::AttributedString)attributedString view:(UIView *)view;
+
+/**
+ @abstract Array of accessibleElements for use in UIAccessibilityContainer implementation.
+*/
+- (NSArray<UIAccessibilityElement *> *)accessibilityElements;
+
+@end

React/Fabric/Mounting/ComponentViews/Text/RCTParagraphComponentAccessibilityProvider.mm

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+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import "RCTParagraphComponentAccessibilityProvider.h"
+
+#import <Foundation/Foundation.h>
+#import <react/components/text/ParagraphProps.h>
+#import <react/textlayoutmanager/RCTTextLayoutManager.h>
+#import <react/textlayoutmanager/TextLayoutManager.h>
+
+#import "RCTConversions.h"
+#import "RCTFabricComponentsPlugins.h"
+
+using namespace facebook::react;
+
+@implementation RCTParagraphComponentAccessibilityProvider {
+  NSMutableArray<UIAccessibilityElement *> *_accessibilityElements;
+  AttributedString _attributedString;
+  __weak UIView *_view;
+}
+
+- (instancetype)initWithString:(AttributedString)attributedString view:(UIView *)view
+{
+  if (self = [super init]) {
+    _attributedString = attributedString;
+    _view = view;
+  }
+  return self;
+}
+
+- (NSArray<UIAccessibilityElement *> *)accessibilityElements
+{
+  // verify if accessibleElements are exist
+  // build an array of the accessibleElements
+  // add first element has the text for the whole textview in order to read out the whole text
+  // add additional elements for those parts of text with embedded link so VoiceOver could specially recognize links
+  // add accessible element for truncation attributed string for automation purposes only
+  _accessibilityElements = [NSMutableArray new];
+  return _accessibilityElements;
+}
+
+@end