useEffect not called in React Native when back to screen

Nomura Nori picture Nomura Nori · Feb 12, 2020 · Viewed 12.6k times · Source

How are you. This is scenario of this issue. Let's say there are 2 screens to make it simple.

  1. enter A screen. useEffect of A screen called.
  2. navigate to B screen from A screen
  3. navigate back to A screen from B. at this time, useEffect is not called.

    function CompanyComponent(props) {
    
       const [roleID, setRoleID] = useState(props.user.SELECTED_ROLE.id)
    
       useEffect(()=>{ 
    
     // this called only once when A screen(this component) loaded,  
     // but when comeback to this screen, it doesn't called
       setRoleID(props.user.SELECTED_ROLE.id)
     }, [props.user])
    }
    

So the updated state of Screen A remain same when comeback to A screen again (Not loading from props)

I am not changing props.user in screen B. But I think const [roleID, setRoleID] = useState(props.user.SELECTED_ROLE.id) this line should be called at least.

I am using redux-persist. I think this is not a problem. For navigation, I use this

// to go first screen A, screen B
function navigate(routeName, params) {
    _navigator.dispatch(
        NavigationActions.navigate({
            routeName,
            params,
        })
    );
}
// when come back to screen A from B
function goBack() {
    _navigator.dispatch(
        NavigationActions.back()
    );
}

Is there any callback I can use when the screen appears? What is wrong with my code?

Thanks

Answer

Nitesh Tosniwal picture Nitesh Tosniwal · Jul 2, 2020

Below solution worked for me:

import React, { useEffect } from "react";
import { useIsFocused } from "@react-navigation/native";

const ExampleScreen = (props) => {
    const isFocused = useIsFocused();

    useEffect(() => {
        console.log("called");
        getInitialData();
    }, [props, isFocused]);

    const getInitialData = async () => {}    

    return (
        ......
        ......
    )
}

I've used react navigation 5+

@react-navigation/native": "5.6.1"