added native iOS functionality for prop currentViewStates

Summary:
Added Native iOS functionality for prop currentViewStates.

On iOS, this property modifies both the view property userInteractionEnabled and also adds corresponding UIAccessibilityTraits to the view.

If disabled is passed in, userInteractionEnabled of the view will be set to false.

The value that is passed into currentviewStates is converted to a UIAccessibilityTrait Enum and masked in with existing UIAccessibilityTraits on that native view.

The native implementation for accessibilityRole is also changed to also mask new UIAccessibilityTraits with existing ones.

Reviewed By: PeteTheHeat

Differential Revision: D8842691

fbshipit-source-id: 919267300c70efed93a7a92377a0178bd8885eb5

Author: Ziqi Chen

React/Views/RCTViewManager.m

@@ -112,7 +112,6 @@ - (RCTShadowView *)shadowView
 RCT_REMAP_VIEW_PROPERTY(accessibilityActions, reactAccessibilityElement.accessibilityActions, NSString)
 RCT_REMAP_VIEW_PROPERTY(accessibilityLabel, reactAccessibilityElement.accessibilityLabel, NSString)
 RCT_REMAP_VIEW_PROPERTY(accessibilityTraits, reactAccessibilityElement.accessibilityTraits, UIAccessibilityTraits)
-RCT_REMAP_VIEW_PROPERTY(accessibilityRole, reactAccessibilityElement.accessibilityTraits, UIAccessibilityTraits)
 RCT_REMAP_VIEW_PROPERTY(accessibilityViewIsModal, reactAccessibilityElement.accessibilityViewIsModal, BOOL)
 RCT_REMAP_VIEW_PROPERTY(accessibilityElementsHidden, reactAccessibilityElement.accessibilityElementsHidden, BOOL)
 RCT_REMAP_VIEW_PROPERTY(accessibilityIgnoresInvertColors, reactAccessibilityElement.shouldAccessibilityIgnoresInvertColors, BOOL)
@@ -149,6 +148,21 @@ - (RCTShadowView *)shadowView
   view.layer.allowsEdgeAntialiasing = !CATransform3DIsIdentity(view.layer.transform);
 }
 
+RCT_CUSTOM_VIEW_PROPERTY(accessibilityRole, UIAccessibilityTraits, RCTView)
+{
+    view.reactAccessibilityElement.accessibilityTraits |= json ? [RCTConvert UIAccessibilityTraits:json] : defaultView.accessibilityTraits;
+}
+
+RCT_CUSTOM_VIEW_PROPERTY(currentViewStates, UIAccessibilityTraits, RCTView)
+{
+    UIAccessibilityTraits traits = json ? [RCTConvert UIAccessibilityTraits:json] : defaultView.accessibilityTraits;
+    view.reactAccessibilityElement.accessibilityTraits |= traits;
+    if (traits == UIAccessibilityTraitNotEnabled || traits == (UIAccessibilityTraitNotEnabled | UIAccessibilityTraitSelected))
+    {
+        view.userInteractionEnabled = NO;
+    } 
+}
+
 RCT_CUSTOM_VIEW_PROPERTY(pointerEvents, RCTPointerEvents, RCTView)
 {
   if ([view respondsToSelector:@selector(setPointerEvents:)]) {