Example code of Swift fingerprint verification function module in iOS development

iOS calls TouchID code:

 override func viewDidLoad() {
    super.viewDidLoad()
    let context = LAContext()
    var error: NSError? = nil
    let canEvaluatePolicy = context.canEvaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, error: &error) as Bool
    if error != nil {
      print(error!.localizedDescription as String)
    }
    if canEvaluatePolicy {
      print(" It has fingerprint verification function ")
      context.evaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, localizedReason: " Put your dog's PAWS on it ", reply: { (success: Bool, error: Error?) in
        if success {
          print(" Authentication is successful ")
        } else {
          print(" Validation fails : \(error?.localizedDescription)")
        }
      })
    } else {
      print(" We haven't turned on fingerprint verification yet ")
    }
  }