Fix logout function - ios

Question

I have the following problem. I try to learn coding since a few weeks and my actually project is an Login-Page.
The concept is the following:
When I open the App, there is the Login Screen and the User can login. This works so far. After the login the user is directed to another view. There is a logout button. And here is the problem. When I click the button, the user get logged out (I proofed this by printing out the current user and got nil) and is returned again to the login screen. But when he is now clicking on the login button without or with wrong data he is getting again to the screen although it appeared the error message.
Where is my fault?
Here is my code:
import UIKit
import Parse
class ViewController: UIViewController {
func displayAlert(title:String, message:String){
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { (action) in self.dismiss(animated: true, completion: nil)}))
self.present(alert, animated: true, completion: nil)
}
#IBOutlet weak var benutzer: UITextField!
#IBOutlet weak var passwort: UITextField!
#IBAction func ButtonLogin(_ sender: Any) {
// Hier die Loginfunktion
let activityIndiaktor = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
activityIndiaktor.center = self.view.center
activityIndiaktor.hidesWhenStopped = true
activityIndiaktor.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.gray
view.addSubview(activityIndiaktor)
activityIndiaktor.startAnimating()
UIApplication.shared.beginIgnoringInteractionEvents()
PFUser.logInWithUsername(inBackground: benutzer.text!, password: passwort.text!, block: { (user, error) in
if user == nil {
var errortext = "Unknown Error! Try again!"
if let error = error {
errortext = error.localizedDescription
}
self.displayAlert(title: "Login error", message: errortext)
}else{
print("Login done!")
let viewController:UIViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Main") as! UIViewController
self.present(viewController, animated: true, completion: nil)
// UIApplication.shared.endIgnoringInteractionEvents()
// activityIndiaktor.stopAnimating()
}
activityIndiaktor.stopAnimating()
UIApplication.shared.endIgnoringInteractionEvents()
return
})
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
And here for the other view:
import UIKit
import Parse
class MainViewController: UIViewController {
#IBAction func Logout(_ sender: Any) {
PFUser.logOut()
let viewController:UIViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LoginSeite") as! UIViewController
self.present(viewController, animated: true, completion: nil)
}
#IBOutlet weak var LabelWillkommen: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
let user = String(describing: PFUser.current()!.username!)
LabelWillkommen.text = "Welcome \(user)!"
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}

Answer 1

In your MainViewController Just change your logout button action with below code snippet
#IBAction func Logout(_ sender: Any) {
PFUser.logOut()
if PFUser.current()?.sessionToken == nil {
let viewController:UIViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LoginSeite") as! UIViewController
self.present(viewController, animated: true, completion: nil)
}
}
Hope this will help you

Answer 2

I checked everything again. I couldn't find the mistake. The Logout works but the if case still thinks, the user is logged in. Can I maybe reload the View or reload the if statement or something like that? Or other ideas?