Update accessibilityState prop

Summary:
Changelog:
[Internal] - Add default value for accessibilityState "checked" and handle unhandled states.

It is also work for the case that accessibilityRole = "switch" and accessibilityState is set.

Reviewed By: sammy-SC

Differential Revision: D22914427

fbshipit-source-id: 4767a21f3bd109019b57bc09918758a38fbdea93

React/Fabric/Mounting/ComponentViews/View/RCTViewComponentView.mm

@@ -516,6 +516,30 @@ - (NSString *)accessibilityLabel
   return RCTRecursiveAccessibilityLabel(self);
 }
 
+- (NSString *)accessibilityValue
+{
+  auto const &props = *std::static_pointer_cast<ViewProps const>(_props);
+
+  // Handle states which haven't already been handled.
+  if (props.accessibilityState.checked == AccessibilityState::Checked) {
+    return @"checked";
+  }
+  if (props.accessibilityState.checked == AccessibilityState::Unchecked) {
+    return @"unchecked";
+  }
+  if (props.accessibilityState.checked == AccessibilityState::Mixed) {
+    return @"mixed";
+  }
+  if (props.accessibilityState.expanded) {
+    return @"expanded";
+  }
+  if (props.accessibilityState.busy) {
+    return @"busy";
+  }
+
+  return nil;
+}
+
 #pragma mark - Accessibility Events
 
 - (NSArray<UIAccessibilityCustomAction *> *)accessibilityCustomActions

ReactCommon/react/renderer/components/view/AccessibilityPrimitives.h

@@ -47,7 +47,7 @@ constexpr enum AccessibilityTraits operator&(
 struct AccessibilityState {
   bool disabled{false};
   bool selected{false};
-  enum { Unchecked, Checked, Mixed } checked{Unchecked};
+  enum { Unchecked, Checked, Mixed, None } checked{None};
   bool busy{false};
   bool expanded{false};
 };

ReactCommon/react/renderer/components/view/accessibilityPropsConversions.h

@@ -125,13 +125,17 @@ inline void fromRawValue(const RawValue &value, AccessibilityState &result) {
     if (checked->second.hasType<std::string>()) {
       if ((std::string)checked->second == "mixed") {
         result.checked = AccessibilityState::Mixed;
+      } else {
+        result.checked = AccessibilityState::None;
       }
     } else if (checked->second.hasType<bool>()) {
       if ((bool)checked->second == true) {
         result.checked = AccessibilityState::Checked;
       } else {
         result.checked = AccessibilityState::Unchecked;
       }
+    } else {
+      result.checked = AccessibilityState::None;
     }
   }
   auto busy = map.find("busy");