有什么设置我不见了？

let myContext = LAContext()
let myLocalizedReasonString = "You are pretty"

var authError: NSError?
if #available(iOS 8.0,macOS 10.12.1,*) {
    if myContext.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics,error: &authError) {
        myContext.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics,localizedReason: myLocalizedReasonString) { success,evaluateError in
            if success {

                print("// User authenticated successfully,take appropriate action")
            } else {
                 print(" // User did not authenticate successfully,look at error and take appropriate action")
            }
        }
    } else {
         print(" // Could not evaluate policy; look at authError and present an appropriate message to user")
    }
} else {
     print(" // Fallback on earlier versions")
}