UseEffect

 import React, { useEffect, useState } from "react";

import { View, Button} from "react-native";

const Test = () => {

const [condition,setCondition]= useState(false);

    useEffect(() => {

       

        console.log(condition);

    }, [condition]);

    const btnClick = () => {

        setCondition((condition)=>!condition);

    }

    return (<View style={{ alignContent: 'center', flex: 1, justifyContent: "center" }}>

     

        <Button title="click" color="red" onPress={btnClick}></Button>

    </View>)

}

export default Test

When click "click" btn then call btnclick  function and change condtion  value false to true .

when will be change value of condtion then useEffect() will be callback