关闭当前呈现的所有 UIAlertControllers
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【中文标题】关闭当前呈现的所有 UIAlertControllers【英文标题】：Dismiss all UIAlertControllers currently presented 【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 【参考方案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)"【参考方案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。【参考方案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】：
【参考方案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】：
【参考方案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。【参考方案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】：
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