How to use AlertController in if-else condition statements - ios

Question

I'm creating a function in my Login View controller. Where if the users password or email Address is incorrect he gets an alert saying 'Login not Successful'. But if the users password and email matches he gets to segue to the Dashboard view controller.
func alert(response:String) {
let alert = UIAlertController(title: "Login Failure", message: "Incorrect Email Address, Phone Number or Password", preferredStyle: .alert)
if response == "Login in not sucessful" {
alert.addAction(UIAlertAction(title:"Okay", style: .cancel,handler:nil))
alert.dismiss(animated: true, completion: nil)
self.present(alert, animated: true, completion: nil)
} else if response == "Login Successful" {
self.performSegue(withIdentifier: "dashboardSegue", sender: self)
}
But whenever I tap the Log in button I either get one of these errors:
Warning: Attempt to present <myApp.customTabBar: 0x7fe68a889800> on <myApp.ViewController: 0x7fe68a606f90> while a presentation is in progress!
Warning: Attempt to present <UIAlertController: 0x7fe68b853e00> on myApp.ViewController: 0x7fe68a606f90> while a presentation is in progress!
Warning: Attempt to present <UIAlertController: 0x7fe68b815400> on <myApp.ViewController: 0x7fe68a475240> whose view is not in the window hierarchy!
the alert shows only once and the app segues anyways to the dashboard viewcontroller even though the users email and password are incorrect. I'm thinking maybe its the if-condition statement. I don't whats wrong. I've checked other questions but I can't quite use the viewDidAppear method because I don't want the alert to appear on startup. Newbie Here , Thanks for any help !!!

Answer 1

Change following line of code will fix your issue.
alert.addAction(UIAlertAction(title:"Okay", style: .cancel,handler:nil))
alert.dismiss(animated: true, completion: nil)
self.present(alert, animated: true, completion: nil)
To
alert.addAction(UIAlertAction(title:"Okay", style: .cancel, handler:nil))
self.present(alert, animated: true, completion: nil)