Implement nativeID prop to allow native code to reference react managed views in iOS

Reviewed By: javache

Differential Revision: D5228055

fbshipit-source-id: 8c934501d4ac946d80bf93d2ddb50f5fc38aea3c

React/Views/RCTViewManager.m

@@ -114,6 +114,8 @@ RCT_EXPORT_VIEW_PROPERTY(hasTVPreferredFocus, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(tvParallaxProperties, NSDictionary)
 #endif
 
+RCT_EXPORT_VIEW_PROPERTY(nativeID, NSString)
+
 // Acessibility related properties
 RCT_REMAP_VIEW_PROPERTY(accessible, reactAccessibilityElement.isAccessibilityElement, BOOL)
 RCT_REMAP_VIEW_PROPERTY(accessibilityLabel, reactAccessibilityElement.accessibilityLabel, NSString)

React/Views/UIView+React.h

@@ -24,6 +24,11 @@
 - (void)insertReactSubview:(UIView *)subview atIndex:(NSInteger)atIndex NS_REQUIRES_SUPER;
 - (void)removeReactSubview:(UIView *)subview NS_REQUIRES_SUPER;
 
+/**
+ * The native id of the view, used to locate view from native codes
+ */
+@property (nonatomic, copy) NSString *nativeID;
+
 /**
  * Layout direction of the view.
  * Internally backed to `semanticContentAttribute` property.

React/Views/UIView+React.m

@@ -27,6 +27,16 @@
   objc_setAssociatedObject(self, @selector(reactTag), reactTag, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
 }
 
+- (NSNumber *)nativeID
+{
+  return objc_getAssociatedObject(self, _cmd);
+}
+
+- (void)setNativeID:(NSNumber *)nativeID
+{
+  objc_setAssociatedObject(self, @selector(nativeID), nativeID, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+}
+
 #if RCT_DEV
 
 - (RCTShadowView *)_DEBUG_reactShadowView