Manage users in firebase for multi tenant app - ios

Question

We have a ordering system which end users can order meals from their iOS app. Each iOS app belongs to a brand, each user also belongs to a brand. We put all brand information in one firebase project. The database structure is:
-brands
-- brand_id_1:
-- information
-- brand_id_2:
-- information
-stores
-- store_id_1:
-- brand_id:brand_id_1
-- more information
-- store_id_2:
-- brand_id:brand_id_1
-- more information
-orders
--brand_id_1:
--order_id_1:
--orderinfo
--brand_id_2:
--order_id_4:
--orderinfo
-users
-- user_id_1:
-- brand_id:brand_id_1
-- userinfo
-- user_id_2:
-- brand_id:brand_id_2
-- userinfo
We use Facebook and twitter authentication for sign in each app. However, one firebase project can only assign one Facebook app id. That means if user downloads brand1 app and sign in by Facebook , when he or she downloads brand2 app, the user account will be already created and our users will be confused. We hope each brand has their own user database, but we can still manage all the brands and stores data in one firebase project.
What we want to do is put all brands and stores in a main firebase project, then for each brand just create a firebase project for each iOS app. These firebase projects are just for user login (when sign up success put the uid to main firebase project), and all user orders will be saved to our main firebase project.
Is it possible? or any other better solutions?

Answer 1

Whenever you need an isolated set of users for an app, you will need a new project for that app. You can use multiple databases per project following the instructions in this article (it is for Android, but it's similar for iOS -
you will have to initialize a new Firebase app in the client for each project you want to use).

Answer 2

After several hours of study, I come up with other approach. The idea is:
Use Facebook iOS sdk to sign in from iOS app and get Facebook token.
iOS app sends this token to cloud functions, fetch user profile using Graph api, then create custom token from Facebook uid.
Send this custom token back to iOS app.
iOS app uses this token to sign in to firebase.
iOS code :
func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!) {
if let token = result.token {
print(token.userID)
print(token.appID)
signInuser(with: token)
}
}
func signInuser(with token:FBSDKAccessToken) {
Alamofire.request("https://xxx.cloudfunctions.net/verifyFacebookUser", method: .post, parameters: ["token":token.tokenString]).responseJSON(completionHandler: { (response) in
switch response.result {
case .success(let data):
if let json = data as? [String:String] {
FIRAuth.auth()?.signIn(withCustomToken: json["token"]!, completion: { (user, err) in
if let error = err {
print(error)
}else {
print(user!.displayName)
print(user!.email)
}
})
}
case .failure( let error):
print(error)
}
})
}
cloud functions:
const functions = require('firebase-functions');
const admin = require('firebase-admin');
const graph = require('fbgraph');
var serviceAccount = require("./serviceAccountKey.json");
admin.initializeApp({
credential: admin.credential.cert(serviceAccount),
databaseURL: "https://xxx.firebaseio.com"
});
exports.verifyFacebookUser = functions.https.onRequest((req,res) => {
if (!req.body.token) {
return res.status(400).send('Access Token not found');
}
graph.setAccessToken(req.body.token);
graph.get("me?fields=id,name,email", function(err, result) {
const firebaseUid = "fb:"+result.id;
admin.auth().createUser({
uid:firebaseUid,
displayName:result.name,
email:result.email
}).then(function(userRecord){
console.log(userRecord)
admin.auth().createCustomToken(userRecord.uid)
.then(function(customToken) {
res.send({token:customToken});
})
.catch(function(error) {
console.log("Error creating custom token:", error);
})
});
});
});
With this method, the iOS app of each brand will ask user to agree sign in from Facebook even if he or she already sign in from different brand app. However that means iOS app needs to implement Facebook native sign in process which Firebase SDK already provide.