initialRoute: PropTypes.shape({
      /**
       * The React Class to render for this route
       */
      component: PropTypes.func.isRequired,
      /**
       * The title displayed in the navigation bar and the back button for this
       * route.
       */
      title: PropTypes.string.isRequired,
      /**
       * If set, a title image will appear instead of the text title.
       */
      titleImage: Image.propTypes.source,
      /**
       * Use this to specify additional props to pass to the rendered
       * component. `NavigatorIOS` will automatically pass in `route` and
       * `navigator` props to the comoponent.
       */
      passProps: PropTypes.object,
      /**
       * If set, the left navigation button image will be displayed using this
       * source. Note that this doesn't apply to the header of the current
       * view, but to those views that are subsequently pushed.
       */
      backButtonIcon: Image.propTypes.source,
      /**
       * If set, the left navigation button text will be set to this. Note that
       * this doesn't apply to the left button of the current view, but to
       * those views that are subsequently pushed
       */
      backButtonTitle: PropTypes.string,
      /**
       * If set, the left navigation button image will be displayed using
       * this source.
       */
      leftButtonIcon: Image.propTypes.source,
      /**
       * If set, the left navigation button will display this text.
       */
      leftButtonTitle: PropTypes.string,
      /**
       * This function will be invoked when the left navigation bar item is
       * pressed.
       */
      onLeftButtonPress: PropTypes.func,
      /**
       * If set, the right navigation button image will be displayed using
       * this source.
       */
      rightButtonIcon: Image.propTypes.source,
      /**
       * If set, the right navigation button will display this text.
       */
      rightButtonTitle: PropTypes.string,
      /**
       * This function will be invoked when the right navigation bar item is
       * pressed.
       */
      onRightButtonPress: PropTypes.func,
      /**
       * Styles for the navigation item containing the component.
       */
      wrapperStyle: View.propTypes.style,
      /**
       * Boolean value that indicates whether the navigation bar is hidden.
       */
      navigationBarHidden: PropTypes.bool,
      /**
       * Boolean value that indicates whether to hide the 1px hairline
       * shadow.
       */
      shadowHidden: PropTypes.bool,
      /**
       * The color used for the buttons in the navigation bar.
       */
      tintColor: PropTypes.string,
      /**
       * The background color of the navigation bar.
       */
      barTintColor: PropTypes.string,
       /**
       * The text color of the navigation bar title.
       */
      titleTextColor: PropTypes.string,
       /**
       * Bboolean value that indicates whether the navigation bar is
       * translucent.
       */
      translucent: PropTypes.bool,
    }).isRequired,