有没有办法关闭当前呈现的所有UIAlertControllers？
这特别是因为从我的应用程序的任何地方和任何状态，当按下推送通知时，我需要访问某个视图控制器。
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！
编辑：适用于iOS 13 +
func dismissAnyAlertControllerIfPresent() {
guard let window = windows.first(where: { $0.isKeyWindow }),
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)
}
}
您可以对UIAlertController进行子类化，将NSNotification观察器附加到每个观察器，这将触发UIAlertController子类中的一种方法来关闭警报控制器，然后在准备关闭时发布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)
}
}
然后在您准备好消除警报时发布通知(在本例中，按下推送通知时(：
NSNotificationCenter.defaultCenter().postNotificationName("DismissAllAlertsNotification", object: nil)
您可以
通过以下方式关闭当前向用户显示的UIAlertController：
self.dismissViewControllerAnimated(true, completion: nil)
我在 swift 4 中编写了更多通用代码，此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)
}
}
以这种方式使用它
//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/需要在应用程序中自动关闭警报时发布通知
let DismissAllAlertsNotification = Notification.Name("DismissAllAlertsNotification")
NotificationCenter.default.post(name: DismissAllAlertsNotification, object: nil)
它们是模态的：任何时候都只有一个，它将具有完全的焦点。
你有责任创建警报，用户应该消除警报。如果需要进一步控制，则需要创建(或使用(自定义视图来显示消息堆栈。
我使用以下扩展来实现这一点，希望对您有所帮助
首先;您将有一个用于UIApplication的扩展来检索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)
}
}