Ported TabBarIOS to OSS and unified implementation

ReactKit/Views/RCTViewNodeProtocol.h

@@ -0,0 +1,35 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+/**
+
+ * Logical node in a tree of application components. Both `ShadowView`s and
+ * `UIView+ReactKit`s conform to this. Allows us to write utilities that
+ * reason about trees generally.
+ */
+@protocol RCTViewNodeProtocol <NSObject>
+
+@property (nonatomic, copy) NSNumber *reactTag;
+
+- (void)insertReactSubview:(id<RCTViewNodeProtocol>)subview atIndex:(NSInteger)atIndex;
+- (void)removeReactSubview:(id<RCTViewNodeProtocol>)subview;
+- (NSMutableArray *)reactSubviews;
+- (id<RCTViewNodeProtocol>)reactSuperview;
+- (NSNumber *)reactTagAtPoint:(CGPoint)point;
+
+// View is an RCTRootView
+- (BOOL)isReactRootView;
+
+@optional
+
+// TODO: Deprecate this
+// This method is called after layout has been performed for all views known
+// to the RCTViewManager. It is only called on UIViews, not shadow views.
+- (void)reactBridgeDidFinishTransaction;
+
+@end
+
+// TODO: this is kinda dumb - let's come up with a
+// better way of identifying root react views please!
+static inline BOOL RCTIsReactRootView(NSNumber *reactTag) {
+  return reactTag.integerValue % 10 == 1;
+}