How to perform segue ONLY if token not nil swift 5 - swift

Question

As the title is saying, im working on a login. The tokenHandler is already working and im using a KeychainAccess.
Here my tokenHandler class:
import KeychainAccess
class TokenHandler {
func saveUsernameToKeyChain(username: String) {
do {
try keychain.set(username, key: "myUsername")
} catch let error {
print(error)
}
}
func getUsernameFromKeyChain() -> String? {
return keychain[string: "myUsername" ]
}
func saveUserPasswordToKeyChain(password: String) {
do {
try keychain.set(password, key: "UserPassword")
} catch let error {
print(error)
}
}
func getUserPasswordFromKeyChain() -> String? {
return keychain[string: "UserPassword"]
}
let keychain = Keychain(service: "com.mybackendpage")
func getTokenFromKeyChain() -> String? {
return keychain[string: "myToken"]
}
func saveTokenToKeyChain(token: String) {
do {
try keychain.set(token, key: "myToken")
}
catch let error {
print(error)
}
}
func saveRefreshTokenToKeyChain(refreshToken: String) {
do {
try keychain.set(refreshToken, key: "myRefreshToken")
}
catch let error {
print(error)
}
}
func loginToAPI(username: String, password: String) -> Any {
guard let url = URL(string: "https:mypage.com") else
{
return ""
}
let jsonData = try? JSONSerialization.data(withJSONObject: [
"email": username,
"password": password
])
var request = URLRequest(url: url)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
// insert json data to the request
request.httpBody = jsonData
URLSession.shared.dataTask(with: request) { (data, response, error) in
guard error == nil else { print(error!.localizedDescription); return }
guard let data = data else { print("Empty data"); return }
if let str = String(data: data, encoding: .utf8) {
print(str)
}
}.resume()
return "TOKENSTRING"
}
}
And here my LoginVC class:
class LoginViewController: UIViewController {
let tokenHandler = TokenHandler()
#IBOutlet weak var usernameTextField: UITextField!
#IBOutlet weak var passwordTextField: UITextField!
#IBOutlet weak var activityIndicator: UIActivityIndicatorView!
override func viewDidLoad() {
super.viewDidLoad()
let username = tokenHandler.getUsernameFromKeyChain()
let userPassword = tokenHandler.getUserPasswordFromKeyChain()
#IBAction func unwindToLogin(_ unwindSegue: UIStoryboardSegue) {
print("-unwinding success-")
}
// func for the login button:
#IBAction func loginButton(_ sender: UIButton) {
activityIndicator.startAnimating()
loginWithCredentials()
let token = tokenHandler.getTokenFromKeyChain()
if token != nil {
performSegue(withIdentifier: "segueToNavigation", sender: self)
} else if ( token == nil ){
// create the alert:
let alert = UIAlertController(title: "Wrong login data", message: "Please try again.", preferredStyle: UIAlertController.Style.alert)
// add an action to the button:
alert.addAction(UIAlertAction( title: "Ok", style: UIAlertAction.Style.default, handler: nil ))
// show the alert:
self.presentingViewController
print("-Token could not be created.-")
}
else {
// create the alert:
let alert = UIAlertController(title: "Wrong login data", message: "Please try again.", preferredStyle: UIAlertController.Style.alert)
// add an action to the button:
alert.addAction(UIAlertAction( title: "Ok", style: UIAlertAction.Style.default, handler: nil ))
// show the alert:
self.presentingViewController
print("-Token could not be created.-")
}
}
func loginWithCredentials() {
let username: String = usernameTextField.text!
let password: String = passwordTextField.text!
let authResponse = tokenHandler.loginToAPI(username: username, password: password)
}
}
Im still not skilled swift programmer, so I will be happy if any of you could give me some good advices. I was reading and trying to work with the delegate principle, but frankly, my guts are telling me, that this is not what I need.
I was reading about
PerformSegueWithIdentifier
but not really understand how to transform it into my code...
The segues which I have included storyboardwise are working, but unfortunately also, if the test user didn't do the login. So, im pressing the login button w/o any username and userpwd and im getting anyway to the next View. Not cool, so help me please :)
EDIT: I changed performSegue to shouldPerformSegue but im still getting access to the next View w/o any permission.
EDIT: Im getting:
-Token could not be created.-
{"message":"The given data was invalid.","errors":{"email":["The email field is required."],"password":["The password field is required."]}}
So the error is correct, but by pressing on the "Login" Button im still getting to the next View.
EDIT:
Ive tried a few changes, now I have for eg:
if tokenHandler.getTokenFromKeyChain() != nil
instead of
let token = tokenHandler.getTokenFromKeyChain()
if token != nil
Apparently, nothing what im doing in this IBAction for the LoginButton does anything different. What am I missing?

Answer 1

Well, it looks to me, that if you did once call saveTokenToKeyChain() ever since you've been running the app on your device/simulator, then the KeyChain will hold some string there, as I can't see where you set it to nil (I can't see where you set it at all, but let's suppose that you deleted the code that saves the token). So what your current logic does is that it performs the segue if you have some string saved as token (no matter if it's empty string, random string or an expired token). Whatever was left there, getTokenFromKeyChain() will return you a string so your if token != nil will always evaluate to true.
On the other hand, if you clear the KeyChain data, as I can't find any piece of code that saves the token, the UI will always say that the login fails, even if it actually succeeds.
So you should handle the login success/failure with properly writing/deleting the token to/from KeyChain.