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我有一个应用程序，我需要非常安全。因此，前台应用程序的用户需要通过 TouchID、FaceID 或他们的电话密码验证自己才能继续。

我能够显示和删除coverVC，但是在我BackgroundViewController的（充当 的那个coverVC）中，我想在应用程序处于前台时提示用户进行生物身份验证

我正在尝试将一个handler函数传递BackgroundViewController给在正确的时间触发，但它不起作用，我不清楚我做错了什么。会喜欢这里的任何帮助。谢谢！

在我的AppDelegate：

func applicationWillResignActive(_ application: UIApplication) {
    coverVC = BackgroundViewController()
    coverWindow = UIWindow(frame: UIScreen.main.bounds)
    let existingTopWindow = UIApplication.shared.windows.last

    coverWindow?.windowLevel = existingTopWindow!.windowLevel + 1
    coverVC!.view.frame = coverWindow!.bounds
    coverWindow?.rootViewController = coverVC
    coverWindow?.makeKeyAndVisible()
}

func applicationDidBecomeActive(_ application: UIApplication) {
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
    if coverWindow != nil {
        self.coverVC?.handler = {
            DispatchQueue.main.async {
                UIView.animate(withDuration: 0.3, delay: 0, options: .curveEaseInOut, animations: {
                    self.coverVC?.view.alpha = 0
                }) { _ in
                    self.coverWindow!.isHidden = true
                    self.coverWindow!.rootViewController = nil
                    self.coverWindow = nil
                    self.coverVC = nil
                }
            }
        }

        self.coverVC?.authenticateReturningUser()
    }
}

在我的BackgroundViewController.swift：

class BackgroundViewController: UIViewController {
   var handler: (() -> Void) = {}

   (viewDidLoad and other stuff in here)

   func authenticateReturningUser() {
    let context = LAContext()
    var error: NSError?

    if context.canEvaluatePolicy(.deviceOwnerAuthentication, error: &error) {
        let reason = "Verify that this is your device to continue."

        context.evaluatePolicy(.deviceOwnerAuthentication, localizedReason: reason) { [weak self] success, error in
            DispatchQueue.main.async {
                if success {
                    if let _self = self {
                        _self.handler()
                    } else {
                        print("this is hitting")
                    }
                }
            }
        }
    }

private func showError(title: String, message: String, buttonText text: String = "Okay") {
    let ac = UIAlertController(title: title, message: message, preferredStyle: .actionSheet)
    ac.addAction(UIAlertAction(title: text, style: .default) { _ in
        self.handler()
        NotificationCenter.default.post(name: NSNotification.Name(rawValue: "LogOut"), object: nil)
    })

    present(ac, animated: true)
}

编辑：

如果我设置[weak self]并[unowned self]调用self.handler()，我会得到：

致命错误：尝试读取无主引用但对象已被释放

4

1 回答 1

1

您的context对象正在被释放。

将您的代码更改为此，因此上下文对象有一个引用

var context: LAContext!
func authenticateReturningUser() {
    context = LAContext()
    var error: NSError?
    if context.canEvaluatePolicy(.deviceOwnerAuthentication, error: &error) {
        let reason = "Verify that this is your device to continue."

        context.evaluatePolicy(.deviceOwnerAuthentication, localizedReason: reason) { [weak self] success, error in
            DispatchQueue.main.async {
                if success {
                    if let _self = self {
                        _self.handler()
                    } else {
                        print("this is hitting")
                    }
                }
            }
        }
    }
}
于 2018-01-25T18:15:55.477 回答