ios - TouchID activateTouchWithResponse 返回成功而不请求指纹

Question

如许多地方所述，我有以下 LocalAuthentication 实现。

context.evaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics, localizedReason: "Logging in with Touch ID", reply: { (success : Bool, error : NSError? ) -> Void in
        dispatch_async(dispatch_get_main_queue(), {

        if success {
            let alert = UIAlertController(title: "Success", message: "", cancelButtonTitle: "Great!")
            self.presentViewController(alert, animated: true, completion: nil)
        }

        if let error = error {
            var message :String

            switch(error.code) {
            case LAError..AuthenticationFailed:
                message = "There was a problem verifying your identity."
            case LAError..UserCancel:
                message = "You pressed cancel."
            case LAError..UserFallback:
                message = "You pressed password."
            default:
                message = "Touch ID may not be configured"
            }

            let alert = UIAlertController(title: "Error", message: message, cancelButtonTitle: "Darn!")
            self.presentViewController(alert, animated: true, completion: nil)
        }
    })
})

但是在我成功通过指纹验证后，evaluatePolicy(, localizedReason:, reply:) 返回成功而不请求任何指纹。我实际上是在使用 UISwitch 启用或禁用 TouchID，因此在禁用并重新启用之后，我想重新验证并重新输入我的指纹。

为什么要缓存身份验证？

谢谢

Answer 1

LAContext 一旦被评估，将返回成功，直到它被释放。您可以手动使其无效，然后返回的错误将是 LAError.InvalidContext。

如果你想每次都提示 TouchID 确认，你需要每次都创建一个 LAContext。这可以实现

context.evaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics, localizedReason: "Logging in with Touch ID", reply: { (success : Bool, error : NSError? ) -> Void in
        dispatch_async(dispatch_get_main_queue(), {

        if success {
            let alert = UIAlertController(title: "Success", message: "", cancelButtonTitle: "Great!")
            self.presentViewController(alert, animated: true, completion: nil)
        }

        if let error = error {
            var message :String

            switch(error.code) {
            case LAError..AuthenticationFailed:
                message = "There was a problem verifying your identity."
            case LAError..UserCancel:
                message = "You pressed cancel."
            case LAError..UserFallback:
                message = "You pressed password."
            default:
                message = "Touch ID may not be configured"
            }

            let alert = UIAlertController(title: "Error", message: message, cancelButtonTitle: "Darn!")
            self.presentViewController(alert, animated: true, completion: nil)
        }

        context = LAContext()
    })
})