Touch ID 成功设置一个变量

Question

我正在尝试根据触摸 ID success/failure return 判断真假。但是当调用 success if 条件时，该函数以假值退出。我是 iOS 开发的新手。我相信我应该使用某种完成处理程序，但在这种特定情况下我不明白如何使用。

func authenticateUser(reasonString: String) -> Bool {
    // Get the local authentication context.
    let context = LAContext()

    // Declare a NSError variable.
    var error: NSError?

    // Current authorization status of user
    var isAuthorized = false

    // Check if the device can evaluate the policy.
    if context.canEvaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics, error: &error) {
        [context .evaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics, localizedReason: reasonString, reply: { (success: Bool, evalPolicyError: NSError?) -> Void in

            if success {
                isAuthorized = true
            }
            else{
                // If authentication failed then show a message to the console with a short description.
                // In case that the error is a user fallback, then show the password alert view.
                print(evalPolicyError?.localizedDescription)

                switch evalPolicyError!.code {

                case LAError.SystemCancel.rawValue:
                    print("Authentication was cancelled by the system")

                case LAError.UserCancel.rawValue:
                    print("Authentication was cancelled by the user")

                case LAError.UserFallback.rawValue:
                    print("User selected to enter custom password")

                default:
                    print("Authentication failed")

                }
            }

        })]
    }
    else{
        // If the security policy cannot be evaluated then show a short message depending on the error.
        switch error!.code{

        case LAError.TouchIDNotEnrolled.rawValue:
            print("TouchID is not enrolled")

        case LAError.PasscodeNotSet.rawValue:
            print("A passcode has not been set")

        default:
            // The LAError.TouchIDNotAvailable case.
            print("TouchID not available")
        }

        // Optionally the error description can be displayed on the console.
        print(error?.localizedDescription)

    }
return isAuthorized
}

即使在执行 touchID 部分之前，此函数 return 也是错误的。有人可以指导吗？

Answer 1

您的函数 authenticateUser 将始终 return false，因为您 return isAuthorized 值将 ti 设置为 false。 context.canEvaluatePolicy 和 context.evaluatePolicy 仍在执行，并且 isAuthorized 的值未更改。

实际流程是这样的：

设置 isAuthorized== false

{call context.canEvaluatePolicy --> 仍在执行调用 context.evaluatePolicy --> 成功 context.canEvaluatePolicy}

Return isAuthorized = False --> context.canEvaluatePolicy 和 context.evaluatePolicy 仍在执行。

执行流程完成方法执行，即使块方法正在执行。

我的建议是从函数末尾删除 return isAuthorized 并实现成功和失败块。

Touch ID 成功设置一个变量

Touch ID on success set a variable

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