footballApp-appAuthScreenExample.js

// All necessary imports 

class AppAuthScreen extends Component {
  
  async componentDidMount() {
    const { navigation } = this.props;
    
    const currentEmail = await AsyncStorage.getItem(
      '@footballApp:currentEmail' // key used to save email during user singup
    );
    
    // if email value exists, it means that it's returning user, so take him to login page
    navigation.navigate(currentEmail ? 'LoginScreen' : 'SignUpNavigator');
  }

  render() {
    return (
      <View style={styles.container}>
        <ActivityIndicator size="large" />
      </View>
    );
  }
}

export default AppAuthScreen;