How to know if face id is enabled

Question

First of all, why is touch id "enabled" to every app but not face id. So if you have touch id set up every app can use it, but face id requires for user to accept it for every app.

How to find if user enabled face id for my app.

This is code i use to find out type of autentification

    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 // Find out if it is enabled
                case .touchID: return .touchID
                }
            } else {
                return .passcode
            }
        } else {
            return .none
        }
    } else {
        if hasAuthentication {
            if hasAuthenticationBiometrics {
                return .touchID
            } else {
                return .passcode
            }
        } else {
            return .none
        }
    }

If user has face id but disabled it for my app, i always get that he "has" face id even though my app is authenticated with passcode?

Answer 1

Found the answer, you use error pointer to find out if user disabled face id.

    var error: NSError?
    let hasAuthenticationBiometrics = myContext.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error)
    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 error?.code == -6 ? .passcode : .faceID // If user disabled face id in settings use passcode
                case .touchID: return .touchID
                }
            } else {
                return .passcode
            }
        } else {
            return .none
        }
    }