关闭当前呈现的所有 UIAlertControllers答案

【问题标题】：Dismiss all UIAlertControllers currently presented关闭当前呈现的所有 UIAlertControllers
【发布时间】：2015-02-20 19:22:30
【问题描述】：

有没有办法关闭当前显示的所有 UIAlertController？

这特别是因为在我的应用程序的任何地方和任何状态下，当按下推送通知时，我都需要访问某个 ViewController。

【问题讨论】：

all UIAlertControllers 是什么意思？所有的 UIAlertController 都呈现了吗？
@CeceXX 显示的任何 UIAlertController。编辑标题和文本以指定
所以你不想展示 UIAlertController 或者你想解雇那些展示的人？
我想关闭当前显示的 UIAlertControllers。
查看我的 Github UIAlertController 项目，我使用队列集中了 UIAlertController 的显示，您可以轻松修改代码以从那里发布通知

标签： ios swift uiwindow uialertcontroller

【解决方案1】：

func dismissAnyAlertControllerIfPresent() {
    guard let window :UIWindow = UIApplication.shared.keyWindow , var topVC = window.rootViewController?.presentedViewController else {return}
    while topVC.presentedViewController != nil  {
        topVC = topVC.presentedViewController!
    }
    if topVC.isKind(of: UIAlertController.self) {
        topVC.dismiss(animated: false, completion: nil)
    }
}

这对我有用！

【讨论】：

这适用于 ios 14 吗？我尝试了几种方法，但没有一种方法有效:(
不错。只是为了最新的 swift 将 ".keyWindow" 替换为 ".windows.first(where: \.isKeyWindow)"

【解决方案2】：

您可以将UIAlertControllers 子类化，将NSNotification 观察者附加到每个观察者，这将触发UIAlertController 子类中的一个方法来关闭警报控制器，然后在您准备关闭时发布NSNotification，例如：

class ViewController: UIViewController {
    func presentAlert() {
        // Create alert using AlertController subclass
        let alert = AlertController(title: nil, message: "Message.", preferredStyle: UIAlertControllerStyle.Alert)
        // Add observer to the alert
        NSNotificationCenter.defaultCenter().addObserver(alert, selector: Selector("hideAlertController"), name: "DismissAllAlertsNotification", object: nil)
        // Present the alert
        self.presentViewController(alert, animated: true, completion:nil)
    }
}

// AlertController subclass with method to dismiss alert controller
class AlertController: UIAlertController {
    func hideAlertController() {
        self.dismissViewControllerAnimated(true, completion: nil)
    }
}

然后在您准备好关闭警报时发布通知（在这种情况下，当按下推送通知时）：

NSNotificationCenter.defaultCenter().postNotificationName("DismissAllAlertsNotification", object: nil)

【讨论】：

@Vov4yk 我在发布之前测试了这段代码，它对我有用。
@Vov4yk 但还要注意，我从未修改过该子类中 UIAlertController 的任何内容...我只是添加了一个新方法，即 hideAlertController。
你有没有向appStore提交过这样的解决方案？我害怕被拒绝，因为子类化
@Vov4yk 文档状态：“此类的视图层次结构是私有的，不得修改。”但是我的解决方案没有修改视图层次结构，所以我不明白为什么应用程序审查会有问题。文档还指出，“UIAlertController 类旨在按原样使用，不支持子类化。”但由于我的解决方案有效，UIAlertController 显然支持这种实际上不会改变视图结构的子类化。
查看我的 Github UIAlertController 项目，我使用队列集中了 UIAlertController 的显示，您可以轻松修改代码以从那里发布通知。

【解决方案3】：

您可以通过这种方式关闭当前呈现给用户的UIAlertController：

self.dismissViewControllerAnimated(true, completion: nil)

【讨论】：

【解决方案4】：

它们是模态的：在任何时候都只会有一个，并且会全神贯注。

创建警报是您的责任，并且应该由用户解除警报。如果您需要进一步控制，则需要制作（或使用）自定义视图来显示一堆消息。

【讨论】：

【解决方案5】：

我在 swift 4 中编写了更通用的代码，该类使用实用程序类显示警报。

import UIKit

let APP_ORANGE_COLOR = UIColor(red: 1.000, green: 0.412, blue: 0.000, alpha: 1.00)

extension UIAlertController {
    @objc func hideAlertController() {
        self.dismiss(animated: false, completion: nil)
    }
}

class AlertUtility: UIViewController {

    static func showAlert(title: String!, message : String!, viewController: UIViewController) {
        let alert = UIAlertController(title: title, message: message ,preferredStyle: UIAlertControllerStyle.alert)

        alert.addAction(UIAlertAction(title: NSLocalizedString("ok", comment: "ok"), style: UIAlertActionStyle.cancel, handler: nil))
        alert.view.tintColor = APP_ORANGE_COLOR

        NotificationCenter.default.addObserver(alert, selector: #selector(alert.hideAlertController), name: DismissAllAlertsNotification, object: nil)

        viewController.present(alert, animated: true, completion: nil)
    }

    static func showAlertAutoDismiss(title: String!, message : String!) -> Void {
        //let appDelegate = UIApplication.shared.delegate as! AppDelegate

        // the alert view
        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)

        let topWindow = UIWindow(frame: UIScreen.main.bounds)
        topWindow.rootViewController = UIViewController()
        topWindow.windowLevel = UIWindowLevelAlert + 0.8

        topWindow.makeKeyAndVisible()
        topWindow.rootViewController?.present(alert, animated: true, completion: {})

        // change to desired number of seconds (in this case 5 seconds)
        let when = DispatchTime.now() + 1
        DispatchQueue.main.asyncAfter(deadline: when){
            // your code with delay
            alert.dismiss(animated: true, completion: nil)
            topWindow.isHidden = true
        }
    }

    static func showAlert(title: String!, message : String!) -> Void {
        //let appDelegate = UIApplication.shared.delegate as! AppDelegate

        // the alert view
        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)

        let topWindow = UIWindow(frame: UIScreen.main.bounds)
        topWindow.rootViewController = UIViewController()
        topWindow.windowLevel = UIWindowLevelAlert + 1
        topWindow.makeKeyAndVisible()
        topWindow.rootViewController?.present(alert, animated: true, completion: {})

        alert.addAction(UIAlertAction(title: NSLocalizedString("ok", comment: "ok"), style: UIAlertActionStyle.cancel, handler: {(_ action: UIAlertAction) -> Void in
            // continue your work
            // important to hide the window after work completed.
            // this also keeps a reference to the window until the action is invoked.
            topWindow.isHidden = true
        }))

        NotificationCenter.default.addObserver(alert, selector: #selector(alert.hideAlertController), name: DismissAllAlertsNotification, object: nil)
        alert.view.tintColor = APP_ORANGE_COLOR
    }


    static func showGenericErrorMessageAlert(viewController: UIViewController) {
        let alert = UIAlertController(title: NSLocalizedString("error", comment: ""), message: NSLocalizedString("generic.error.message", comment: "") ,preferredStyle: UIAlertControllerStyle.alert)

        alert.addAction(UIAlertAction(title: NSLocalizedString("ok", comment: "ok"), style: UIAlertActionStyle.cancel, handler: nil))
        alert.view.tintColor = APP_ORANGE_COLOR
        viewController.present(alert, animated: true, completion: nil)
        NotificationCenter.default.addObserver(alert, selector: #selector(alert.hideAlertController), name: DismissAllAlertsNotification, object: nil)
    }

    static func showComingSoonAlert(viewController: UIViewController) {

        // the alert view
        let alert = UIAlertController(title: "", message: NSLocalizedString("coming.soon", comment: ""), preferredStyle: .alert)

        viewController.present(alert, animated: true, completion: {})

        // change to desired number of seconds (in this case 5 seconds)
        let when = DispatchTime.now() + 1
        DispatchQueue.main.asyncAfter(deadline: when){
            // your code with delay
            alert.dismiss(animated: true, completion: nil)
        }
        NotificationCenter.default.addObserver(alert, selector: #selector(alert.hideAlertController), name: DismissAllAlertsNotification, object: nil)
    }

    // Show alert view with call back
    static func showAlertWithCB(title: String, message: String, isConditional: Bool, viewController: UIViewController, completionBlock: @escaping (_: Bool) -> Void) {

        let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
        alert.view.tintColor = APP_ORANGE_COLOR
        // Check whether it's conditional or not ('YES' 'NO, or just 'OK')
        if isConditional
        {
            alert.addAction(UIAlertAction(title: NSLocalizedString("cancel", comment: ""), style: UIAlertActionStyle.cancel, handler: { (action: UIAlertAction) in
                alert.dismiss(animated: true, completion: nil)
                completionBlock(false)
            }))

            alert.addAction(UIAlertAction(title: NSLocalizedString("yes", comment: ""), style: UIAlertActionStyle.default, handler: { (action: UIAlertAction) in
                alert.dismiss(animated: true, completion: nil)
                completionBlock(true)
            }))

        }
        else
        {
            alert.addAction(UIAlertAction(title: NSLocalizedString("ok", comment: "ok"), style: UIAlertActionStyle.default, handler: { (action: UIAlertAction) in
                alert.dismiss(animated: true, completion: nil)
                completionBlock(true)
            }))
        }

        NotificationCenter.default.addObserver(alert, selector: #selector(alert.hideAlertController), name: DismissAllAlertsNotification, object: nil)
        viewController.present(alert, animated: true, completion: nil)
    }

    static func showAlertWithTextField(viewController : UIViewController,completionBlock: @escaping (_: Bool, String) -> Void) {

        //1. Create the alert controller.
        let alert = UIAlertController(title: "Report Event?", message: "", preferredStyle: .alert)
        alert.view.tintColor = APP_ORANGE_COLOR
        //2. Add the text field. You can configure it however you need.
        //AlertUtility.addte
        alert.addTextField { (textField) in

            let heightConstraint = NSLayoutConstraint(item: textField, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 50)
            textField.addConstraint(heightConstraint)
            textField.placeholder = "Enter report reason here"
            textField.tintColor = APP_ORANGE_COLOR
            textField.autocapitalizationType = .sentences
        }

        // 3. Grab the value from the text field, and print it when the user clicks OK.
        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { [weak alert] (_) in
            // Force unwrapping because we know it exists.
            completionBlock(true,"")
            //print("Text field: \(textField.text)")
        }))

        // 3. Grab the value from the text field, and print it when the user clicks OK.
        alert.addAction(UIAlertAction(title: "Submit", style: .default, handler: { [weak alert] (_) in
            let textField = alert?.textFields![0] // Force unwrapping because we know it exists.
            completionBlock(true,(textField?.text)!)
            //print("Text field: \(textField.text)")
        }))

        // 4. Present the alert.
        viewController.present(alert, animated: true, completion: nil)

        let textField = alert.textFields![0]
        let v = UIView.init(frame: textField.frame)
        textField.addSubview(v)
        v.frame = textField.frame
        v.bounds = textField.bounds
        v.backgroundColor = APP_ORANGE_COLOR
        v.superview?.bringSubview(toFront: v)
    }

}

这样使用

//sample code - use in your view controller
AlertUtility.showAlertWithCB(title: NSLocalizedString("alert", comment: "") , message: (error)!, isConditional: false, viewController: self, completionBlock: { (yes) in

                      //Your actions on callback
                        self.popToPreviousController()
                    })
AlertUtility.showAlert(title: ALERT_TITLE, message: message, viewController: self)

当您想要/需要在应用中自动关闭警报时发布通知

let DismissAllAlertsNotification = Notification.Name("DismissAllAlertsNotification")

NotificationCenter.default.post(name: DismissAllAlertsNotification, object: nil)

【讨论】：

这是一个在实现自动注销功能时非常有用的代码。应用程序自动重定向到登录屏幕，但屏幕上仍保留警报。

【解决方案6】：

我使用以下扩展来实现这一点，希望它可以帮助你

首先；你将有一个 UIApplication 扩展来检索 RootViewController

extension UIApplication {

   static func topViewControllerInNavigationStack(controller: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
       if let navigationController = controller as? UINavigationController {
            return topViewControllerInNavigationStack(controller: navigationController.visibleViewController)
       }
       if let tabController = controller as? UITabBarController {
           if let selected = tabController.selectedViewController {
             return topViewControllerInNavigationStack(controller: selected)
           }
       }
       if let presented = controller?.presentedViewController {
           return topViewControllerInNavigationStack(controller: presented)
       }
       return controller
   }
}

第二； UIAlertViewController 的扩展

extension UIAlertController {
     static func dismissPresentedAlertViewController() {
         let viewController = UIApplication.topViewControllerInNavigationStack()
         guard let isKindOf = viewController?.isKind(of: 
         UIAlertController.classForCoder()), isKindOf else {
             return
         }
         viewController?.dismiss(animated: false, completion: nil)
    }
}

【讨论】：