RealmSwift currentUser cannot be called if more that one valid, logged-in user exists - swift

Question

I have a realm platform and I can register and login a user fine. When I try to open a Synced Realm file with the current User it will not allow it and Xcode throws the error currentUser cannot be called if more that one valid, logged-in user exists. I have followed all the information I can find on realms docs and I can't make sense as to why this is happening. I have a Login View Controller and a separate View Controller that contains the realm file. Here is example code of the problem I am dealing with.
LogInViewController
import Cocoa
import RealmSwift
class LoginViewController: NSViewController {
#IBOutlet weak var username: NSTextField!
#IBOutlet weak var password: NSSecureTextField!
let realm = try! Realm()
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func loginButtonPressed(_ sender: NSButton) {
let login = SyncCredentials.usernamePassword(username: "\(username.stringValue)", password: "\(password.stringValue)", register: false)
SyncUser.logIn(with: login, server: Constants.AUTH_URL, onCompletion: { [weak self] (user, err) in
if let _ = user {
if let mainWC = self?.view.window?.windowController as? MainWindowController {
mainWC.segueToHome()
print("Login Pressed")
}
} else if let error = err {
fatalError(error.localizedDescription)
}
})
}
}
SecondViewController
import Cocoa
import RealmSwift
class ViewController: NSViewController {
#IBOutlet weak var textField: NSTextField!
override func viewDidLoad() {
super.viewDidLoad()
let config = SyncUser.current!.configuration(realmURL: Constants.REALM_URL, fullSynchronization: false, enableSSLValidation: true, urlPrefix: nil)
self.realm = try! Realm(configuration: config)
}
func save(data: Data) {
do {
try realm.write {
realm.add(data)
}
} catch {
print("there was an error saving data \(error)")
}
}
#IBAction func saveData(_ sender: NSButton) {
let saveData = Data()
saveData.textField = textField.stringValue
save(data: data)
}
func loadData() {
data = realm.objects(Data.self).sorted(byKeyPath: "timestamp", ascending: false)
}
}

Answer 1

Maybe, this page help you solve the problem.
I solved the same problem.
///
/// quit all other users session
///
for u in SyncUser.all {
u.value.logOut()
}
///
///
///
let creds: SyncCredentials = SyncCredentials.usernamePassword(
username: YOUR_USER,
password: YOUR_PASS
)
SyncUser.logIn(
with: creds,
server: YOUR_AUTH_URL
) { (user: SyncUser?, err: Error?) in
///
/// Your action ...
///
}
After logOut and logIn, this method will success probably.
let config = SyncUser.current!.configuration(realmURL: Constants.REALM_URL, fullSynchronization: false, enableSSLValidation: true, urlPrefix: nil)
self.realm = try! Realm(configuration: config)

Answer 2

If you are using Realm with Firebase, a snippet like this will save you from authentication headaches.
Check to see if the SyncUser uid matches the uid from firebase, and sign out extraneous accounts.
for syncUser in SyncUser.all {
if(syncUser.key != (FirebaseAuth.Auth.auth().currentUser?.uid ?? "")) {
syncUser.value.logOut()
}
}