How to programmatically check support of 'Face

Question

I've integrated LocalAuthentication for my app security purpose, which has been supporting 'Touch Id' based supporting. But now, apple has recently added 'Face Id' based authentication also.

How can I check, which type of authentication is supported by a device. Touch Id or Face Id?

Answer 1

I've been struggling to get this to work and found that I needed to use a single instance of the LAContext and needed to call the LAContextInstance.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: nil) before getting the biometryType. Here is my final code with support for older iOS versions:

import LocalAuthentication

static func biometricType() -> BiometricType {
    let authContext = LAContext()
    if #available(iOS 11, *) {
        let _ = authContext.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: nil)
        switch(authContext.biometryType) {
        case .none:
            return .none
        case .touchID:
            return .touch
        case .faceID:
            return .face
        }
    } else {
        return authContext.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: nil) ? .touch : .none
    }
}

enum BiometricType {
    case none
    case touch
    case face
}

Answer 2

This code builds without warnings on Xcode 9.2-9.4 (see comments for 9.1):

@objc let biometricsAuthPolicy = LAPolicy.deviceOwnerAuthenticationWithBiometrics

@objc func supportsFaceID() -> Bool {
    if #available(iOS 11.0, *) {
        return biometryType() == .faceID // return biometryType() == .typeFaceID for Xcode 9.1
    }
    return false
}

@objc func supportsTouchID() -> Bool {
    if #available(iOS 11.0, *) {
        return biometryType() == .touchID // return biometryType() == .typeTouchID for Xcode 9.1
    }

    let context = LAContext()
    return context.canEvaluatePolicy(biometricsAuthPolicy, error: nil)
}

@objc @available(iOS 11.0, *)
func biometryType() -> LABiometryType {
    var error: NSError?
    let context = LAContext()

    guard context.canEvaluatePolicy(biometricsAuthPolicy, error: &error) else {
        if #available(iOS 11.2, *) {
            return .none
        }
        return LABiometryType.LABiometryNone // return LABiometryType.none for Xcode 9.1
    }

    return context.biometryType
}

Answer 3

Here is one more way via the property (for example, on your access instance).

import LocalAuthentication


enum BiometricType {
    case none
    case touchID
    case faceID
}

var biometricType: BiometricType {
    get {
        let context = LAContext()
        var error: NSError?

        guard context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) else {
            print(error?.localizedDescription ?? "")
            return .none
        }

        if #available(iOS 11.0, *) {
            switch context.biometryType {
            case .none:
                return .none
            case .typeTouchID:
                return .touchID
            case .typeFaceID:
                return .faceID
            }
        } else {
            return  .touchID
        }
    }
}

Answer 4

As I am a big fan of extension. I phrase this answer a little differently. Essense is the same. This is a drop-in extension.

import LocalAuthentication

extension LAContext {
    enum BiometricType: String {
        case none
        case touchID
        case faceID
    }

    var biometricType: BiometricType {
        var error: NSError?

        guard self.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) else {
            // Capture these recoverable error thru Crashlytics
            return .none
        }

        if #available(iOS 11.0, *) {
            switch self.biometryType {
            case .none:
                return .none
            case .touchID:
                return .touchID
            case .faceID:
                return .faceID
            }
        } else {
            return  self.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: nil) ? .touchID : .none
        }
    }
}

Use like this:

var currentType = LAContext().biometricType

Answer 5

Here is my "helper class", it includes passcode also

enum BiometryType: String {
    case none = "None"
    case faceID = "Face ID"
    case touchID = "Touch ID"
    case passcode = "Passcode"
}


var biometryType: BiometryType {
    let myContext = LAContext()

    let hasAuthenticationBiometrics = myContext.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: nil)
    let hasAuthentication = myContext.canEvaluatePolicy(.deviceOwnerAuthentication, error: nil)

    if #available(iOS 11.0, *) {
        if hasAuthentication {
            if hasAuthenticationBiometrics {
                switch myContext.biometryType {
                case .none: return .none
                case .faceID: return .faceID
                case .touchID: return .touchID
                }
            } else {
                return .passcode
            }
        } else {
            return .none
        }
    } else {
        if hasAuthentication {
            if hasAuthenticationBiometrics {
                return .touchID
            } else {
                return .passcode
            }
        } else {
            return .none
        }
    }
}

Answer 6

With Xcode 9, Look at LocalAuthentication -> LAContext -> LABiometryType.

LABiometryType is a enum with values as in attached image

You can check which authentication type supported by device between Touch ID and FaceID or none.

Edit:

Apple have updated values for this enum LABiometryType. none is deprecated now.