Authentication failed and Try Face Id Again does nothing

Question

I'm just follow this tutorial to authenticate user by Face ID but actually it's not work with "Try Face Id Again" button after authentication failed, the callback was not called and I don't know why. Here is the code:

@IBAction func touchIdAction(_ sender: UIButton) {

    print("hello there!.. You have clicked the touch ID")

    let myContext = LAContext()
    let myLocalizedReasonString = "Biometric Authntication testing !! "

    var authError: NSError?
    if #available(iOS 8.0, macOS 10.12.1, *) {
        if myContext.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &authError) {
            myContext.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: myLocalizedReasonString) { success, evaluateError in

                DispatchQueue.main.async {
                    if success {
                        // User authenticated successfully, take appropriate action
                        self.successLabel.text = "Awesome!!... User authenticated successfully"
                    } else {
                        // User did not authenticate successfully, look at error and take appropriate action
                        self.successLabel.text = "Sorry!!... User did not authenticate successfully"
                    }
                }
            }
        } else {
            // Could not evaluate policy; look at authError and present an appropriate message to user
            successLabel.text = "Sorry!!.. Could not evaluate policy."
        }
    } else {
        // Fallback on earlier versions

        successLabel.text = "Ooops!!.. This feature is not supported."
    }


}

Running with Xcode 9.4.1 on iPhone X Simulator. Thanks

Answer 1

Before tapping Try Face Id Again button you have to inform the simulator if it should simulate matching or non-matching face.

You can do it by selecting Hardware->Face ID->Matching Face/Non-matching Face