Presenting view controller from detached view controller is discouraged. Keeping User logged in issue - swift

Question

I'm trying to have the user move to automatically go to the Home Screen and not have to log in again. Basically, to remember the user. I used User Defaults to save the user login info and put the listener for the key in the viewDidLoad of the first login page. I used an if statement to switch the view controllers but it doesn't work and prints (Presenting view controller from detached view controller is discouraged).
LoginViewController:
import UIKit
import FirebaseAuth
import AVKit
class LoginViewController: UIViewController {
var videoPlayer:AVPlayer?
var videoPlayerLayer:AVPlayerLayer?
#IBOutlet weak var emailTextField: UITextField!
#IBOutlet weak var Back: UIButton!
#IBOutlet weak var passwordtextField: UITextField!
#IBOutlet weak var loginButton: UIButton!
#IBOutlet weak var errorLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
setupElements()
}
func dismissKeyboard() {
//Causes the view (or one of its embedded text fields) to resign the first responder status.
view.endEditing(true)
}
func setupElements(){
errorLabel.alpha = 0
Utilities.styleTextField(emailTextField)
Utilities.styleTextField(passwordtextField)
Utilities.styleFilledButton(loginButton)
}
func validateFields() -> String?
{
//make sure fields are filled
if emailTextField.text?.trimmingCharacters(in: .whitespacesAndNewlines) == "" || passwordtextField.text?.trimmingCharacters(in: .whitespacesAndNewlines) == ""
{
return "Please fill all fields"
}
return nil
}
#IBAction func loginTapped(_ sender: Any) {
//creates a clean version of the text field
let email = emailTextField.text!.trimmingCharacters(in: .whitespacesAndNewlines)
let password = passwordtextField.text!.trimmingCharacters(in: .whitespacesAndNewlines)
let error = validateFields()
//sign in user
Auth.auth().signIn(withEmail: email, password: password) { (result, error) in
UserDefaults.standard.set(Auth.auth().currentUser!.uid, forKey: "user_uid_key")
UserDefaults.standard.synchronize()
if error != nil{
self.errorLabel.text = "Invalid Username/Password try again."
self.errorLabel.alpha = 1
}
else{
let homeViewController = self.storyboard?.instantiateViewController(identifier: Constants.StoryBoard.homeViewController) as?
HomeViewController
self.view.window?.rootViewController = homeViewController
self.view.window?.makeKeyAndVisible()
}
}
//make sure all fields are filled
}
override func viewWillAppear(_ animated: Bool) {
setUpVideo()
}
func setUpVideo(){
//Get path to resource bundle
let bundlePath = Bundle.main.path(forResource: "IMG_7211 2", ofType: "mov")
guard bundlePath != nil else{
return
}
//create the url from it
let url = URL(fileURLWithPath: bundlePath!)
//Create The video Player item
let item = AVPlayerItem(url: url)
//create the player
videoPlayer = AVPlayer(playerItem: item)
//create the layer
videoPlayerLayer = AVPlayerLayer(player: videoPlayer!)
//adjust the size and frame
videoPlayerLayer?.frame = CGRect(x: -self.view.frame.size.width*1.5, y:0, width: self.view.frame.size.width*4, height: self.view.frame.size.height)
view.layer.insertSublayer(videoPlayerLayer!, at: 0)
//add and play
videoPlayer?.playImmediately(atRate: 0.8)
}
}
ViewController:
import UIKit
import AVKit
import Firebase
import FirebaseAuth
class ViewController: UIViewController {
var videoPlayer:AVPlayer?
var videoPlayerLayer:AVPlayerLayer?
#IBOutlet weak var signUpButton: UIButton!
#IBOutlet weak var logInButton: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
if UserDefaults.standard.object(forKey: "user_uid_key") != nil {
print("i see u")
let navController = UINavigationController(rootViewController: HomeViewController())
navController.navigationBar.barStyle = .black
self.present(navController, animated: false, completion: nil)
}
else {
let homeViewController = self.storyboard?.instantiateViewController(identifier: Constants.StoryBoard.homeViewController) as?
ViewController
self.view.window?.rootViewController = homeViewController
self.view.window?.makeKeyAndVisible()
}
// Do any additional setup after loading the view.
setupElements()
}
func showhomepage() {
let homeViewController = self.storyboard?.instantiateViewController(identifier: Constants.StoryBoard.homeViewController) as?
HomeViewController
self.view.window?.rootViewController = homeViewController
self.view.window?.makeKeyAndVisible()
}
override func viewWillAppear(_ animated: Bool) {
//Set up video in background
setUpVideo()
}
func setUpVideo(){
//Get path to resource bundle
let bundlePath = Bundle.main.path(forResource: "Project", ofType: "mp4")
guard bundlePath != nil else{
return
}
//create the url from it
let url = URL(fileURLWithPath: bundlePath!)
//Create The video Player item
let item = AVPlayerItem(url: url)
//create the player
videoPlayer = AVPlayer(playerItem: item)
//create the layer
videoPlayerLayer = AVPlayerLayer(player: videoPlayer!)
//adjust the size and frame
videoPlayerLayer?.frame = CGRect(x: -self.view.frame.size.width*1.5, y:0, width: self.view.frame.size.width*4, height: self.view.frame.size.height)
view.layer.insertSublayer(videoPlayerLayer!, at: 0)
//add and play
videoPlayer?.playImmediately(atRate: 1)
}
func setupElements(){
Utilities.styleFilledButton(signUpButton)
Utilities.styleHollowButton(logInButton)
}
}

Answer 1

Looks like you're using Firebase. Do not store any login information in the User defaults. What you should do is create a blank view controller that will check if the user is signed in. If the user is signed it, it will present your HomeViewController; if the user is not signed in, it will present the login screen. You can also choose to perform these checks in your AppDelegate/SceneDelegate if you want to avoid the extra view controller.
The empty ViewController should be the initial/root ViewController.
You cannot present view controllers from inside viewDidLoad, use viewDidAppear.
Here is a basic example for the view controller way:
// in the new empty view controller, import FirebaseAuth
var handle: AuthStateDidChangeListenerHandle!
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(false)
handle = Auth.auth().addStateDidChangeListener { auth, user in
if user != nil {
// Go to Home Screen/ switch root
} else {
// Go to sign in screen/ switch root
}
}
}