Hides react view button until view size calculated

lib/ios/RNNUIBarButtonItem.m

 	reactView.sizeFlexibility = RCTRootViewSizeFlexibilityWidthAndHeight;
 	reactView.delegate = self;
 	reactView.backgroundColor = [UIColor clearColor];
-	reactView.clipsToBounds = YES;
+	reactView.hidden = YES;
 	
 	self.widthConstraint = [NSLayoutConstraint constraintWithItem:reactView
 														attribute:NSLayoutAttributeWidth
 }
 
 - (void)rootViewDidChangeIntrinsicSize:(RCTRootView *)rootView {
+	rootView.hidden = NO;
 	self.widthConstraint.constant = rootView.intrinsicContentSize.width;
 	self.heightConstraint.constant = rootView.intrinsicContentSize.height;
 	[rootView setNeedsUpdateConstraints];