Minimal version to get Google Sign in working with Supabase on IOS in React Native with Expo. If you are not using Expo, follow the setup guide of `react-native-app-auth` instead of using `rn-app-auth-plugin.js` and `app.json`.

app.json

{
  ...
  
    "plugins": [
      [
        "./rn-app-auth-plugin"
      ]
    ],
  ...
}

App.tsx

import { Session } from '@supabase/supabase-js';
import supabase from './util/supabase';
import { useEffect, useState } from 'react';
import AuthForm from './components/AuthForm';

export default function App() {
  const [session, setSession] = useState<Session | null>(null)

  useEffect(() => {
    supabase.auth.getSession().then(({ data: { session } }) => {
      setSession(session)
    })

    supabase.auth.onAuthStateChange((_event, session) => {
      setSession(session)
    })
  }, []);
  
  return session && session.user ? <INSERT_YOUR_CONTENT_HERE> : <AuthForm />;
}

AuthForm.tsx

import React from 'react';
import { Alert, StyleSheet, View } from 'react-native';
import { Button } from 'react-native-elements';
import supabase from '../util/supabase';
import { authorize } from 'react-native-app-auth';

export default function AuthForm() {
    async function authGoogle() {
        const config = {
            issuer: 'https://accounts.google.com',
            clientId: 'GOOGLE_GUID.apps.googleusercontent.com',
            redirectUrl: 'com.googleusercontent.apps.GOOGLE_GUID:/oauth2redirect/google',
            scopes: ['email'],
            useNonce: false,
        };
        try {
            const authState = await authorize(config);
            const { data, error } = await supabase.auth.signInWithIdToken({
                provider: 'google',
                token: authState.idToken,
            })
        } catch (error) {
            Alert.alert('Something went wrong, please try again later');
        }
    }

    return (
        <Button title="[G] Sign in with Google" onPress={() => authGoogle()} />
    )
}

rn-app-auth-plugin.js

const {
  withAppDelegate,
} = require('@expo/config-plugins');


function withRnAppAuth(config) {
  return withAppDelegate(
    config,
    async (
      config
    ) => {
      const xcodeProject = config.modResults;
      xcodeProject.contents = xcodeProject.contents.replace('#import "AppDelegate.h"', `#import <RCTAppDelegate.h>
#import <UIKit/UIKit.h>
#import <Expo/Expo.h>
#import <React/RCTLinkingManager.h>
#import "RNAppAuthAuthorizationFlowManager.h"

@interface AppDelegate : EXAppDelegateWrapper <RNAppAuthAuthorizationFlowManager>

@property(nonatomic, weak) id<RNAppAuthAuthorizationFlowManagerDelegate> authorizationFlowManagerDelegate;

@end`);

      return config;
    }
  );
};

module.exports = withRnAppAuth;

supabase.js

import AsyncStorage from '@react-native-async-storage/async-storage';
import { createClient } from "@supabase/supabase-js";
import { AppState } from "react-native";

const supabase = createClient(
    <INSERT_YOUR_SUPABASE_URL>,
    <INSERT_YOUR_SUPABASE_PUBLIC_KEY>,
    {
        auth: {
            storage: AsyncStorage,
            autoRefreshToken: true,
            persistSession: true,
            detectSessionInUrl: false,
        }
    }
);

AppState.addEventListener('change', (state) => {
    if (state === 'active') {
        supabase.auth.startAutoRefresh()
    } else {
        supabase.auth.stopAutoRefresh()
    }
});

export default supabase;

Minimal version to get Google Sign in working with Supabase on IOS in React Native with Expo. If you are not using Expo, follow the setup guide of react-native-app-auth instead of using rn-app-auth-plugin.js and app.json.