在显示Touch ID提示时，是否可以立即为用户提供输入密码的机会？

Question

当提供Touch ID /本地身份验证以解锁某些内容，并且可以同时使用Touch ID和Passcode时，它只会显示＆＃34; Enter Password＆＃34; 首次尝试Touch ID失败后选项。

是否可以立即显示？我设想一个未经过身份验证的用户在设备上使用Touch ID会尝试使用该应用，如果他们知道密码就可以使用它，并且他们可能不会尝试他们的指纹，因为他们知道它没有被添加。

Answer 1

是的，可以使用带密码的 Touch ID

• 适用于 Apple Face ID（iPhone X、Xs、XR、XsMax）和其他配备 Touch ID 的设备。
• 识别失败时的预定义错误处理。
• 在多次失败尝试时使用设备密码自动进行身份验证。

使用 BiometricAuthentication 在您的应用中使用 Apple FaceID 或 TouchID 身份验证。它非常简单易用，可根据设备处理 Touch ID 和 Face ID 身份验证。

请检查这个例子:-

• Apple Touch ID

有两种选择

• .deviceOwnerAuthenticationWithBiometrics

• deviceOwnerAuthentication

  extension ViewController {
  
  func authenticationWithTouchID() {
   let localAuthenticationContext = LAContext()
   localAuthenticationContext.localizedFallbackTitle = "Use Passcode"
  
   var authError: NSError?
   let reasonString = "To access the secure data"
  
   if localAuthenticationContext.canEvaluatePolicy(.deviceOwnerAuthentication, error: &authError) {
  
       localAuthenticationContext.evaluatePolicy(.deviceOwnerAuthentication, localizedReason: reasonString) { success, evaluateError in
  
           if success {
               print("User authenticated successfully")
               //TODO: User authenticated successfully, take appropriate action
  
           } else {
               //TODO: User did not authenticate successfully, look at error and take appropriate action
               guard let error = evaluateError else {
                   return
               }
  
               print(self.evaluateAuthenticationPolicyMessageForLA(errorCode: error._code))
  
               //TODO: If you have choosen the 'Fallback authentication mechanism selected' (LAError.userFallback). Handle gracefully
  
           }
       }
   } else {
  
       guard let error = authError else {
           return
       }
       //TODO: Show appropriate alert if biometry/TouchID/FaceID is lockout or not enrolled
       print(self.evaluateAuthenticationPolicyMessageForLA(errorCode: error.code))
   }
  }
  
  func evaluatePolicyFailErrorMessageForLA(errorCode: Int) -> String {
   var message = ""
   if #available(iOS 11.0, macOS 10.13, *) {
       switch errorCode {
           case LAError.biometryNotAvailable.rawValue:
               message = "Authentication could not start because the device does not support biometric authentication."
  
           case LAError.biometryLockout.rawValue:
               message = "Authentication could not continue because the user has been locked out of biometric authentication, due to failing authentication too many times."
  
           case LAError.biometryNotEnrolled.rawValue:
               message = "Authentication could not start because the user has not enrolled in biometric authentication."
  
           default:
               message = "Did not find error code on LAError object"
       }
   } else {
       switch errorCode {
           case LAError.touchIDLockout.rawValue:
               message = "Too many failed attempts."
  
           case LAError.touchIDNotAvailable.rawValue:
               message = "TouchID is not available on the device"
  
           case LAError.touchIDNotEnrolled.rawValue:
               message = "TouchID is not enrolled on the device"
  
           default:
               message = "Did not find error code on LAError object"
       }
   }
  
   return message;
  }
  
  func evaluateAuthenticationPolicyMessageForLA(errorCode: Int) -> String {
  
   var message = ""
  
   switch errorCode {
  
   case LAError.authenticationFailed.rawValue:
       message = "The user failed to provide valid credentials"
  
   case LAError.appCancel.rawValue:
       message = "Authentication was cancelled by application"
  
   case LAError.invalidContext.rawValue:
       message = "The context is invalid"
  
   case LAError.notInteractive.rawValue:
       message = "Not interactive"
  
   case LAError.passcodeNotSet.rawValue:
       message = "Passcode is not set on the device"
  
   case LAError.systemCancel.rawValue:
       message = "Authentication was cancelled by the system"
  
   case LAError.userCancel.rawValue:
       message = "The user did cancel"
  
   case LAError.userFallback.rawValue:
       message = "The user chose to use the fallback"
  
   default:
       message = evaluatePolicyFailErrorMessageForLA(errorCode: errorCode)
   }
  
   return message
   }
  }