Firebase won't jump inside methods - ios

Question

For some reason my firebase methods do things that make no sense to me. I want to login with a user and afterwards check on some data to make a decision. Both methods signIn() and getDocument() don't go beyond the curly brackets. If I set a breakpoint or step over the next point where it stops is outside the curly brackets. What am I doing wrong?
This is the whole code:
import Foundation
import Firebase
//#objc(LoginViewController)
class LoginViewController: UIViewController {
#IBOutlet weak var errorMessage: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
#IBOutlet weak var emailField: UITextField!
#IBOutlet weak var passwordField: UITextField!
#IBAction func didTapEmailLogin(_ sender: UIButton) {
// Check if empty
guard emailField.text != nil, passwordField.text != nil else {
self.errorMessage.text = "Fields can't be empty."
return
}
// Log in
let email = emailField.text!
let password = passwordField.text!
guard login(with: email, with: password) else {
print("Login didn't work")
return
}
// Check if user has a group yet
guard userHasGroup() else {
print("Getting data didn't work")
return
}
}
func userHasGroup() -> Bool {
var succesful = true
let db = Firestore.firestore()
let userUid = Auth.auth().currentUser?.uid
let docRef = db.collection("users").document(userUid!)
docRef.getDocument { (document, _) in
if let document = document, document.exists {
// Test
print(document.data() as! [String: Any])
} else {
succesful = false
}
}
return succesful
}
func login(with email: String, with password: String) -> Bool {
var succesful = true
Auth.auth().signIn(withEmail: email, password: password) { (user, error) in
guard error == nil, user != nil else {
// There was an error.
self.errorMessage.text = "Email/password incorrect."
succesful = false
return
}
}
return succesful
}
}

Answer 1

This is the definition of async behaviour. The first time through your function all the code outside the closure is executed. Then when this async call to signIn returns the code inside the closure is executed.
The problem is the structure of your function. You can't reliably return a value from a function that contains a closure as the value won't be set when the function returns.
You need to change your function to use a completion handler.
I've posted a recent example of how to do this here Why aren't my Firebase Storage URLs uploading to Google Cloud Firestore?

Answer 2

So indeed it was an async problem.
This is how I made it work:
#IBAction func didTapEmailLogin(_ sender: UIButton) {
// Check if empty
guard emailField.text != nil, passwordField.text != nil else {
self.errorMessage.text = "Fields can't be empty."
return
}
let email = emailField.text!
let password = passwordField.text!
loginAsync(with: email, with: password) { (loginSuccesful) in
if loginSuccesful {
self.userHasGroupAsync(completionHandler: { (hasGroup) in
if hasGroup {
self.performSegue(withIdentifier: "fromLoginToHome", sender: self)
} else {
self.performSegue(withIdentifier: "fromLoginToCreateJoinGroup", sender: self)
}
})
}
}
}
func loginAsync(with email: String, with password: String, completionHandler: #escaping (Bool) -> ()) {
var succesful = true
Auth.auth().signIn(withEmail: email, password: password) {
(user, error) in
guard error == nil, user != nil else {
// There was an error.
self.errorMessage.text = "Email/password incorrect."
succesful = false
return
}
completionHandler(succesful)
}
}
func userHasGroupAsync(completionHandler: #escaping (Bool) -> ()) {
var hasGroup = false
let db = Firestore.firestore()
let userUid = Auth.auth().currentUser?.uid
let docRef = db.collection("users").document(userUid!)
docRef.getDocument { (document, _) in
if let document = document, document.exists {
let data: [String: Any] = document.data()!
let group = data["group"] as! String
if group != "" { hasGroup = true }
}
completionHandler(hasGroup)
}
}