I'm using useReducer and context to update my state in App.js then send data to the database but it doesn't update the state and always is null.

App.js

import AuthContext from './context';
import screenA from './screenA';

export default function App() {

 const initialLoginState = {
   email: null,
 };
const loginReducer = (prevState, action) => {
   switch (action.type) {
     case 'Email':
       return {
         ...prevState,
         email: action.Email,
       };
   }
 };

const authContext = React.useMemo(
   () => ({
     email: emailUser => {
       dispatch({type: 'Email', Email: emailUser});
       console.log(loginState.email);
     },
     signIn: async () => {
       try {
         fetch('FakeApi', {
           method: 'POST',
           headers: {
             Accept: 'application/json',
             'Content-Type': 'application/json',
           },
           body: JSON.stringify({
             email: loginState.email,
             date: '2021-9-20',
           }),
         });
       } catch (e) {
         console.log(e);
       }
     },
   }),
   [],
 );
 const [loginState, dispatch] = React.useReducer(
   loginReducer,
   initialLoginState,
 );

return (
   <AuthContext.Provider value={authContext}>
         <screenA />
   </AuthContext.Provider>

Blockquote context

I create a separate context component

context.js

import React from 'react';

export const AuthContext = React.createContext();

Blockquote screenA

In screenA I use email and signIn to send data to App.js and then save this data in the database screenA.js

import {AuthContext} from './context';

function screenA() {
 const {email,signIn} = React.useContext(AuthContext);
 return (
   <View style={{marginTop: 150}}>
     {/* Count: {state.count} */}
     <Button
       title="sent email"
       onPress={() => {
         email('example@gmail.com');
       }}
     />
     <Button
       title="signIn"
       onPress={() => {
         signIn();
       }}
     />
   </View>
 );
}

export default screenA;