SwiftUI App can't get data from Firestore - swift

Question

I will start by explaining with words, then I will explain with code below. Here we go.
I have a struct 'User' that I use in my app. It has important data like username, email, and profileImageUrl. To access a list of users, I need to request a list of users from Firestore. But when I do this, it returns an empty array.
EXCEPT right after I log in. If I check the Users array before I log in, it's empty. If I check the users array after I log in, it's empty. But if I print it inside the .onAppear of the main content view that loads, it prints the true array of users.
I also notice that my program never thinks I'm the current user, even if I am. Each instance of User has a property isCurrentUser: Bool that is supposed to check if the user that is currently logged in is the same user in that instance. But they all appear as false.
It seems to me that the program thinks I'm not logged in, and will only let me pull data from the server if I'm logged in. Even though I changed my Firestore and Firebase Storage rules to allow me to read and write even if I'm not logged in.
Here are important snippets of code.
User struct
struct User : Identifiable {
let id : String
let username : String
let profileImageUrl : String
let email : String
let isCurrentUser: Bool
init (dictionary: [String: Any]) {
self.id = dictionary["uid"] as? String ?? ""
self.username = dictionary["username"] as? String ?? ""
self.profileImageUrl = dictionary["profileImageUrl"] as? String ?? ""
self.email = dictionary["email"] as? String ?? ""
self.isCurrentUser = Auth.auth().currentUser?.uid == self.id
}
}
notice the self.isCurrentUser code. I'm thinking maybe this code isn't working, or that self.id isn't working properly.
I also receive these two errors whenever I unsuccessfully fetch from the Users array.
2021-02-24 21:00:50.172361-0800 Council[38163:1564633] [] nw_protocol_get_quic_image_block_invoke dlopen libquic failed
2021-02-24 21:00:52.168254-0800 Council[38163:1564630] [connection] nw_resolver_start_query_timer_block_invoke [C1] Query fired: did not receive all answers in time for firebaselogging-pa.googleapis.com:443
So please share any knowledge you have this problem is killing me i have to finish this app in time and now I am not able to work due to this bug
Here is my main ContentView that shows login screen if a user isn't logged in, but shows the homepage if a user is logged in. I called an instance of SearchViewModel() to test if I could print SearchViewModel().users. This is the view in which I can get the users array to print, but only right after I log in. If I attempt to print it on a subsequent page, it'll be the same empty array.
import SwiftUI
struct ContentView: View {
#State private var navBarHidden: Bool = true
#EnvironmentObject var viewModel : AuthViewModel
#ObservedObject var searchViewModel = SearchViewModel()
var body: some View {
Group{
if viewModel.userSession != nil{
NavigationView{
TabView{
FeedView(navBarHidden: $navBarHidden)
.navigationBarHidden(self.navBarHidden)
.tabItem{
Image(systemName: "house")
Text("For You")
}
Text("Random")
.tabItem{
Image(systemName: "questionmark.circle")
Text("Random")
}
SearchView()
.tabItem {
Image(systemName: "magnifyingglass")
Text("Search")
}
.navigationBarHidden(true)
}
.accentColor(.black)
.onAppear() {
searchViewModel.fetchUsers()
print(searchViewModel.users)
}
}
} else {
LoginView()
}
}
}
}
More code: Here is my User struct
import Foundation
import Firebase
struct User : Identifiable {
let id : String
let username : String
let profileImageUrl : String
let email : String
let isCurrentUser: Bool
init (dictionary: [String: Any]) {
self.id = dictionary["uid"] as? String ?? ""
self.username = dictionary["username"] as? String ?? ""
self.profileImageUrl = dictionary["profileImageUrl"] as? String ?? ""
self.email = dictionary["email"] as? String ?? ""
self.isCurrentUser = Auth.auth().currentUser?.uid == self.id
}
}
Here is the file for the ViewModel that fetches the users
import SwiftUI
import Firebase
class SearchViewModel: ObservableObject {
#Published var users = [User]()
init() {
fetchUsers()
print("usersFetched")
}
func fetchUsers() {
Firestore.firestore().collection("users").getDocuments { snapshot, _ in
guard let documents = snapshot?.documents else {return}
documents.forEach{ document in
let user = User(dictionary: document.data())
self.users.append(user)
}
}
}
Here is the ViewModel that authenticates users, creates users, and logs them in
import SwiftUI
import Firebase
class AuthViewModel: ObservableObject {
#Published var userSession: FirebaseAuth.User?
#Published var isAuthenticating = false
#Published var error: Error?
#Published var user: User?
init() {
userSession = Auth.auth().currentUser
fetchUser()
}
func login(withEmail email : String, password: String) {
Auth.auth().signIn(withEmail: email, password: password) { result, error in
if let error = error{
print("Failed to upload image. Error: \(error.localizedDescription)")
return
}
self.userSession = result?.user
print("U logged in")
}
}
func registerUser( email : String, password: String, username: String, profileImage: UIImage) {
guard let imageData = profileImage.jpegData(compressionQuality: 0.3) else {return}
let fileName = NSUUID().uuidString
let storageRef = Storage.storage().reference().child(fileName)
storageRef.putData(imageData, metadata: nil) { _, error in
if let error = error{
print("Failed to upload image. Error: \(error.localizedDescription)")
return
}
print("successful upload of photo")
storageRef.downloadURL { url , _ in
guard let profileImageUrl = url?.absoluteString else {return}
Auth.auth().createUser(withEmail: email, password: password) { result, error in
if let error = error {
print("Failed to Register. Error: \(error.localizedDescription)")
return
}
guard let user = result?.user else {return}
let data = ["email": email,
"username": username.lowercased(),
"profileImageUrl": profileImageUrl,
"uid": user.uid]
Firestore.firestore().collection("users").document(user.uid).setData(data) { _ in
self.userSession = user
print("successfully uploaded user data")
}
print("Successful SIgnup")
}
}
}
}
func signOut() {
userSession = nil
try? Auth.auth().signOut()
}
func fetchUser() {
guard let uid = userSession?.uid else {return}
Firestore.firestore().collection("users").document(uid).getDocument { snapshot, _ in
guard let data = snapshot?.data() else {return}
let user = User(dictionary: data)
}
}
}
EDIT: New possibility for an issue. When the users array successfully prints, it does so in this format:
MyApp.User(id: "kugrbub", username: "user1", profileImageUrl: "https://theimageurl.com", email: "ceo#violent.jewelry", isCurrentUser: false),
When it prints, it's in parentheses, not braces. So is this a reason why it could be failing?

Answer 1

I believe I see what's going wrong. I think that you're misunderstanding what is happening with the asynchronous Firebase methods.
When you call a method like .getDocuments in Firebase, that method does not return instantaneously. Rather, it runs asynchronously and then calls your callback function that you provide when it's finished.
Why does this lead to the result that you're getting? In ContentView, you initialize SearchViewModel by calling SearchViewModel() to set up the property. In the init() of SearchViewModel, fetchUsers() is called, which populates the users array when it completes.
Then, once your login completes, ContentView switches over to your NavigationView/TabView, and onAppear is called. Inside, you call fetchUsers again, which starts running asynchronously. But, because you had already called fetchUsers in the SearchViewModel init, the array already has data in it (keep in mind that unless you explicitly sign out of Firebase, you'll still be signed in from the previous session).
So, how do you solve this?
Remember that all of those calls are asynchronous. Printing the arrays right after calling the fetchUsers method(s) will never get you the values you want *unless they had been populated before.
Restructure your app so that you can respond to the changes in the view model asynchronously. Because you have so much going on, there's not one definitive way to clean everything up. But, you can look into a couple of things:
look up onReceive which you can use to tell when a single publisher on your ObservableObject has changed.
When using Firebase, I like using Auth.auth().addStateDidChangeListener to respond to the auth state. That might help you start to split up your login logic.
Instead of printing after your fetchUsers call, print from inside the Firebase callback functions.
A code sample for you:
class SearchViewModel: ObservableObject {
#Published var users = [User]()
func fetchUsers() {
guard Auth.auth().currentUser?.uid != nil else {
assertionFailure("NOT SAFE TO GET USERS YET -- NOT LOGGED IN")
return
}
Firestore.firestore().collection("users").getDocuments { snapshot, _ in
guard let documents = snapshot?.documents else {return}
print("Received docs:")
print(documents)
documents.forEach{ document in
let user = User(dictionary: document.data())
self.users.append(user)
}
print("USERS:")
print(self.users)
}
}
}
struct ShowUsersView: View {
#ObservedObject var searchViewModel = SearchViewModel()
var body: some View {
VStack {
ForEach(searchViewModel.users, id: \.id) { user in
Text(user.username)
}
}.onAppear {
print("Calling fetchUsers...")
searchViewModel.fetchUsers()
}
}
}