How to programmatically check support of 'Face Id' and 'Touch Id'

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
}