Can we test Face ID in simulator?

As you asking but after enabling that, what can I do?

Just like a touch Id enrolment, You can verify things with face-Id on iPhone-X. However simulator have some limitations like Appstore etc. With face-Id enrolment you can do following things -

• Use Face ID to make purchases.
• Sign in with Face ID (Sign in to apps).
• Autofill passwords in Safari.
• In the iTunes Store, App Store, and iBooks Store.

See more at Apple

The simulator just simulates the outcome of a correct and a failed face recognition, just like it does with Touch ID. It does not recognize faces.

Simulator does not recognise a face but allows you to simulate a matching and non-matching faces, if you've enabled Enrolled option from Face ID.

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Add following code to your view controller and try with Face-ID

import LocalAuthentication

class ViewController: UIViewController {


    override func viewDidLoad() {
        super.viewDidLoad()
        localAuthentication()
    }



    func localAuthentication() -> Void {

        let laContext = LAContext()
        var error: NSError?
        let biometricsPolicy = LAPolicy.deviceOwnerAuthenticationWithBiometrics

        if (laContext.canEvaluatePolicy(biometricsPolicy, error: &error)) {

            if let laError = error {
                print("laError - \(laError)")
                return
            }

            var localizedReason = "Unlock device"
            if #available(iOS 11.0, *) {
                if (laContext.biometryType == LABiometryType.faceID) {
                    localizedReason = "Unlock using Face ID"
                    print("FaceId support")
                } else if (laContext.biometryType == LABiometryType.touchID) {
                    localizedReason = "Unlock using Touch ID"
                    print("TouchId support")
                } else {
                    print("No Biometric support")
                }
            } else {
                // Fallback on earlier versions
            }


            laContext.evaluatePolicy(biometricsPolicy, localizedReason: localizedReason, reply: { (isSuccess, error) in

                DispatchQueue.main.async(execute: {

                    if let laError = error {
                        print("laError - \(laError)")
                    } else {
                        if isSuccess {
                            print("sucess")
                        } else {
                            print("failure")
                        }
                    }

                })
            })
        }


    }
}

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FaceID authentication will prompt you for first time to allow FaceID detection for your app.

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Now enable Face ID enrolment and run your app to test Face ID simulation Testing.

Here is simulation result for matching and non-matching faces.

Result for matching face:

Result for non-matching face:

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