Login state management and cache for React Native with Apollo client - react-native

Question

I'm learning graphQL with React native and using the apollo client. I'm experimenting with some code that has a simple login screen and I'm trying to check my understanding of the cache. My graphql client code is below. By turning on the debug for the persistCache I see the line when use CMD + R to reload an iOS simulator with expo. This suggests the cache is working.
[apollo-cache-persist] Restored cache of size 29
My question is what else is needed to complete the overall process of not needing to login again? I assume I need to maintain state on whether it's logged in and not show the login screen. I'm after some examples which show this.
const retryLink = new RetryLink({
delay: {
initial: 300,
max: 5000,
jitter: true
},
attempts: {
max: Infinity,
retryIf: (error = {}) => {
return error.statusCode > 299 || !error.statusCode
}
}
});
const formatObject = data => _.isObject(data) ? JSON.stringify(data) : data;
const formatGraphQLError = err =>
`Message: ${err.message}, Location: ${formatObject(
err.locations
)}`;
const errorLink = onError(({ networkError = "", graphQLErrors = [] } = {}) => {
if (networkError)
console.log(`[Network Error]: ${networkError}`);
if (graphQLErrors.length)
graphQLErrors.map(formatGraphQLError).forEach(err => console.log(`[GraphQL Error]: ${err}`))
});
const authLink = setContext(async (_, { headers }) => {
const token = await Auth.token();
if (token)
return {
headers: {
...headers,
authorization: `Bearer ${token}`
}
};
else return { headers };
});
const httpLink = new HttpLink({
uri: Config.apiUrl
});
const cache = new InMemoryCache();
// Set up cache persistence.
persistCache({
cache,
storage: AsyncStorage,
trigger: 'background',
debug: true
});
const logLink = new ApolloLink((operation, forward) => {
console.log("Running GraphQL query or mutation");
return forward(operation);
});
//--
//-- Combine the links in your required order.
//--
let _notifications = 42;
const client = new ApolloClient({
resolvers: {
Query: {
permission: async (_, { type }) => await Permissions.askAsync(type),
token: async () => await Auth.token(),
notifications: () => _notifications
},
Mutation: {
login: async (_, { email, password }) => {
return await Auth.login(email, password)
},
updateNotifications: async (_, { notifications }) => _notifications = notifications
}
},
link: ApolloLink.from([
logLink,
retryLink,
errorLink,
authLink,
httpLink
]),
cache
});
export default client;