app.jsx

export default class Main extends Component {

  // currentUser stuff is in the state...
  
  
  render() {
    const AppNavigator = createRootNavigator();

    return (
      <SessionContext.Provider value={this.state}>
        <AppNavigator persistenceKey="NavigationState" />
      </SessionContext.Provider>
    );
  }

}

navigation-options.js

export function backNavigation(title, options = {}) {
  return ({navigation}) => {
    const params = navigation.state.params || {};

    return {
      title: title || `${params.title}`,
      headerStyle: {
        backgroundColor: params.toolbarColor || options.color || Colors.FOODEE_RED,
      },
      headerTitleStyle: {
        color: 'white'
      },
      headerLeft: (
        <View style={{marginLeft: 10}}>
          <Icon
            name='chevron-left'
            size={20}
            color="white"
            type='font-awesome'
            style={{paddingLeft: 20}}
            onPress={() => navigation.pop()}
          />
        </View>
      )
    }
  };
}

vehicle-type.jsx

export class VehicleTypeScreen extends Component {

  static navigationOptions = backNavigation('Vehicle Type');

  render() {
    // some stuff
  }


  static propTypes = {
    navigation: PropTypes.object
  };

}

export default function VehicleType(props) {
  return (
    <SessionContext.Consumer>
      {({currentUser}) => (
        <VehicleTypeScreen
          {...props}
          currentUser={currentUser}
        />
      )}
    </SessionContext.Consumer>
  );
}