App crashing when it gets closed because of biometrics - ios

Question

I have followed this tutorial to set up authentication on my app.
It works fine, but when try to terminate the app, I get the following:
* Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Modifications to the
layout engine must not be performed from a background thread after it
has been accessed from the main thread.'
* First throw call stack:
(0x18bf22a48 0x18bc49fa4 0x18c3f8f08 0x18c1fa03c 0x19035664c 0x190357a00 0x18f604c5c 0x18f6004c8 0x18f600734 0x18f600a54
0x18f6054dc 0x18f605328 0x18f5e7004 0x18f97b134 0x18f97b838
0x18f990f70 0x18f989d7c 0x18f98b790 0x18f98dc6c 0x18f98e168
0x18f98dbbc 0x18f98de24 0x100c0f4ec 0x100c01780 0x1017917fc
0x101792bd8 0x1017952d4 0x1017a4160 0x1017a4a88 0x18bc3eb48
0x18bc41760)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
I do not understand the error.
Here's my code:
func authenticateUser() {
let context = LAContext()
var error: NSError?
if context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) {
let reason = "Identify yourself!"
context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason) { [weak self] success, authError in
DispatchQueue.main.async {
if success {
self?.loginSuccessfull()
} else {
DispatchQueue.main.async {
let ac = UIAlertController(title: "Errore", message: "Riprova", preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "Ok", style: .default, handler: { (action) in
self?.authenticateUser()
return
}))
self?.present(ac, animated: true, completion: nil)
}
}
}
}
} else {
let ac = UIAlertController(title: "Errore", message: "Il tuo device non è configurato per l'autenticazione", preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "Ok", style: .default))
self.present(ac, animated: true, completion: nil)
}
if context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) {
let reason = "Identify yourself!"
context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason) {
[unowned self] success, authenticationError in
DispatchQueue.global().async {
if success {
DispatchQueue.main.async {
self.loginSuccessfull()
}
} else {
let ac = UIAlertController(title: "Authentication failed", message: "Sorry!", preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "OK", style: .default))
self.present(ac, animated: true)
}
}
}
} else {
let ac = UIAlertController(title: "Touch ID not available", message: "Your device is not configured for Touch ID.", preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "OK", style: .default))
present(ac, animated: true)
}
}
As you can see, I just evaluate the biometrics. Again: this works perfectly during the whole "life" of the application, but the problem comes out when I terminate the app. It just crashes and gets me to the home screen.
There are no crash logs into Settings > Privacy...

Answer 1

please use for authentication function its a global function
//enum for response handler
enum AuthenticatinsError: String {
case userEnrolled = "User is not enrolled"
case passCodeNotSet = "user not set passcode"
case biometricNotAvelabel = "Biometric authentication not available"
case faild = "faild to authenticat"
case noIssue = ""
}
func authenticationUser(compleation: #escaping (_ status: Bool, _ msgg: AuthenticatinsError) -> Void) {
context = LAContext()
//check inside app if biometric on then in UserDefault set true other wise false
//let isBiometricOn = WUserDefault.getBiometric()
//if isBiometricOn == false {
//context.invalidate()
//}
// First check if we have the needed hardware support.
var error: NSError?
if context.canEvaluatePolicy(.deviceOwnerAuthentication, error: &error) {
let reason = "Log in to your account"
context.evaluatePolicy(.deviceOwnerAuthentication, localizedReason: reason ) { success, error in
if success {
compleation(true, .noIssue)
} else {
print(error?.localizedDescription ?? "Failed to authenticate")
compleation(false, .faild )
}
}
} else {
if let err = error {
if #available(iOS 11.0, *) {
switch err.code {
case LAError.Code.biometryNotEnrolled.rawValue:
notifyUser("User is not enrolled",
err: err.localizedDescription)
compleation(false, .userEnrolled)
case LAError.Code.passcodeNotSet.rawValue:
compleation(false, .passCodeNotSet)
case LAError.Code.biometryNotAvailable.rawValue:
notifyUser("Biometric authentication not available",
err: err.localizedDescription)
compleation(false, .biometricNotAvelabel)
default:
compleation (false, .passCodeNotSet)
}
} else {
// Fallback on earlier versions
}
}
}
}
user code where you call
self.authenticationUser { (statu, msg) in
if statu == true {
DispatchQueue.main.async {
self?.loginSuccessfull()
}
} else {
DispatchQueue.main.async {
let ac = UIAlertController(title: "Errore", message: "Riprova", preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "Ok", style: .default, handler: { (action) in
self?.authenticateUser()
return
}))
self?.present(ac, animated: true, completion: nil)
}
}
}