supabase/examples/ReactNativeTodoList/native/components/UserContext.js

import React, {useEffect, useState, createContext, useContext} from 'react';
import {supabaseClient} from '../lib/initSupabase';

export const UserContext = createContext({
  user: null,
  session: null,
});

export const UserContextProvider = props => {
  const [session, setSession] = useState(null);
  const [user, setUser] = useState(null);

  useEffect(() => {
    const session = supabaseClient.auth.session();
    setSession(session);
    setUser(session?.user ?? null);
    const {data: authListener} = supabaseClient.auth.onAuthStateChange(
      async (event, session) => {
        console.log(`Supabase auth event: ${event}`);
        setSession(session);
        setUser(session?.user ?? null);
      },
    );

    return () => {
      authListener.unsubscribe();
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  const value = {
    session,
    user,
  };
  return <UserContext.Provider value={value} {...props} />;
};

export const useUser = () => {
  const context = useContext(UserContext);
  if (context === undefined) {
    throw new Error('useUser must be used within a UserContextProvider.');
  }
  return context;
};