How to detect whether device support FaceID or not?

Question

Its bit early to ask but I'm planning to add feature specially for FaceID, so before that I need to validate either device support FaceID or not? Need suggestion and help. Thanks in advance.

Answer 1

Objective-C version

- (BOOL) isFaceIdSupported{
    if (@available(iOS 11.0, *)) {
        LAContext *context = [[LAContext alloc] init];
        if ([context canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:nil]){
            return ( context.biometryType == LABiometryTypeFaceID);
        }
    }
    return NO;
}

Answer 2

I found that you have to call canEvaluatePolicy before you will properly get the biometry type. If you don't you'll always get 0 for the raw value.

So something like this in Swift 3, tested and working in Xcode 9.0 & beta 9.0.1.

class func canAuthenticateByFaceID () -> Bool {
    //if iOS 11 doesn't exist then FaceID doesn't either
    if #available(iOS 11.0, *) {
        let context = LAContext.init()

        var error: NSError?

        if context.canEvaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, error: &error) {
            //As of 11.2 typeFaceID is now just faceID
            if (context.biometryType == LABiometryType.typeFaceID) {
                return true
            }
        }
    }

    return false
}

You could of course write that just to see if it's either biometric and return the type along with the bool but this should be more than enough for most to work off of.