message: Fix NavigationBar render issue on iOS.
diff: @@ -28,7 +28,8 @@ var NavigationBar = ({hidden, logo, navIcon, overflowIcon, children, ...otherPro
  logo={Image.resolveAssetSource(logo)}
  navIcon={Image.resolveAssetSource(navIcon)}
  overflowIcon = {Image.resolveAssetSource(overflowIcon)}
  - style={{ height: 50 }}
  + style={Platform.OS === 'android' ? { height: 50 } : undefined}
  + hidden={hidden}
  {...otherProps}
  onActionSelected={({nativeEvent}) => {
  var onPress = menuItems[nativeEvent.position].onPress;
  