React Navigation V5 does not receive focused parameter when using custom bottomTab component

Question

I am currently trying to implement a custom tabBar design into my react native app which is using React Navigation 5 as the navigation library. Everything is working correctly, except that my tabBarIcons don't receive any props, so i cannot determine whether i have to show the active or inactive tabIcon. Whenever i use a default tabbar i do receive the props, so there must be something wrong in my custom tabbar. I did follow the docs though, and only find the instruction to emit the 'tabPress' event. I do however think that i should emit more events to get the correct focused prop. I have set up the navigator like this:

const Tabs = createBottomTabNavigator();

export default () => (
  <Tabs.Navigator tabBar={TabBarComponent} initialRouteName="Home">
    <Tabs.Screen
      name="Home"
      component={HomeScreen}
      options={{
        tabBarIcon: ({ focused }) => {
          // The props here are {}, so focused is undefined.
          const icon = focused
            ? require('images/iconOverviewRed.png')
            : require('images/iconOverviewGrey.png');

          return <Image source={icon} />;
        },
      }}
    />
    <Tabs.Screen
      name="Overview"
      component={OverviewScreen}
      options={{
        tabBarIcon: props => {
          console.log(props);
          return <Image source={require('images/logoRed.png')} />;
        },
      }}
    />
    <Tabs.Screen
      name="Account"
      component={AccountScreen}
      options={{
        tabBarIcon: ({ focused }) => {
          const icon = focused
            ? require('images/iconAccountRed.png')
            : require('images/iconAccountGrey.png');

          return <Image source={icon} resizeMethod="resize" />;
        },
      }}
    />
  </Tabs.Navigator>
);

And this is my custom tabBar compnent:

const TabBar = ({ navigation, state, descriptors }: any) => {
  return (
    <View style={styles.container}>
      {state.routes.map((route: any) => {
        const onPress = () => {
          const event = navigation.emit({
            type: 'tabPress',
            target: route.key,
            canPreventDefault: true,
          });

          if (!event.defaultPrevented) {
            navigation.dispatch({
              ...TabActions.jumpTo(route.name),
              target: state.key,
            });
          }
        };

        return (
          <TabIcon
            key={route.key}
            Icon={descriptors[route.key].options.tabBarIcon}
            onPress={onPress}
            isBig={route.name === 'Home'}
          />
        );
      })}
    </View>
  );
};

const TabIcon = ({ onPress, Icon, key, isBig }: any) => {
  return (
    <TouchableWithoutFeedback key={key} onPress={onPress}>
      <View style={isBig ? styles.bigTab : styles.defaultTab} key={key}>
        <Icon />
      </View>
    </TouchableWithoutFeedback>
  );
};

Thanks in advance.

Answer 1

descriptors[route.key].options just gives you the options as you have specified them. If you log the value of descriptors[route.key].options.tabBarIcon, you'll see that it prints the function that you have specified.

In your custom tab bar, it's upto you to use the option as you need. Since it's a function here, you'll have to call it and pass desired arguments.

descriptors[route.key].options.tabBarIcon({ focused: state.index === index })

This also means that you fully control the option. You can put whatever type you'd like, function, a require statement directly etc. and then use that. You also don't have to call it tabBarIcon, you can call it whatever you want.