[Solved]-React Navigation: How to update navigation title for parent, when value comes from redux and gets updated in child?-Reactjs

My advice:

1. Make sure that ParentScreen is connected through react-redux connect function.

2. If you want the title of ParentScreen to get updated automatically when the state of the store changes, connecting it won't be enough. You will have to use the componentWillReceiveProps like you are doing in the ChildScreen Component.

Bonus: you could create a Higher Order Component for encapsulating that behaviour, like this:

const withTotalTitle = Component => props => {
  class TotalTitle extends Component {
    static navigationOptions = {
      title: ({ state }) => `Total: ${state.params && state.params.count ?  state.params.count : ''}`
    };

    componentWillReceiveProps(nextProps) {
      if (nextProps.count != this.props.count) {
        this.props.navigation.setParams({ count: nextProps.count });
      }
    }

    render() {
      return (
        <Component {...props}/>
      );
    }
  }

  return connect(state => { count: state.total })(TotalTitle); // update this (I have no idea what the structure your state looks like)
};

And then you could use it like this:

const ChildScreen = withTotalTitle(({ increment }) => (
  <View>
    <Button onPress={() => increment()} title="Increment" />
  </View>
));

const ParentScreen = withTotalTitle(() => (
  <View>
    <Text>Whatever ParentScreen is supposed to render.</Text>
  </View>
));