iOS，仅对应用程序功能的子集使用生物特征身份验证答案

【问题标题】：iOS, using biometric authentication only for a subset of an apps functionalityiOS，仅对应用程序功能的子集使用生物特征身份验证
【发布时间】：2018-11-20 19:33:09
【问题描述】：

我正在开发一个应用程序，其中用户只需要对某些功能进行身份验证，但他们应该对其余功能保持“匿名”。当用户尝试访问特定功能时，有没有办法在应用程序中实现生物特征认证？

例如，让我们说，要参与应用程序内的公开讨论论坛，他们不需要进行身份验证，但一旦他们尝试发送直接消息，他们将需要使用 Touch ID 或 Face ID 进行身份验证。可以这样做，还是只能在用户打开应用时使用生物特征认证？

【问题讨论】：

标签： ios swift

【解决方案1】：

是的，您可以在任何您想使用的地方使用它。只需请求身份验证，然后在身份验证成功完成后，显示另一个 ViewController。

【讨论】：

【解决方案2】：

您可以在任何地方进行生物特征验证，您可以尝试以下示例：

func authenticationWithTouchID(completion: (Bool) -> ()) {
    let localAuthenticationContext = LAContext()
    localAuthenticationContext.localizedFallbackTitle = "Use Passcode"

    var authError: NSError?
    let reasonString = "To access the secure data"

    if localAuthenticationContext.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &authError) {

        localAuthenticationContext.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reasonString) { success, evaluateError in
            if success {
                completion(true)
            } else {
                //TODO: User did not authenticate successfully, look at the 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
                completion(false)
            }
        }
    } 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
}

现在您可以在任何地方使用此功能

authenticationWithTouchID(completion: {(success) in
    if success {
         //TODO: User authenticated successfully, take appropriate action     
    } else {
         //TODO: User authenticateion failed, take appropriate action
    }
})

【讨论】：