ios - 从 AppDelegate 到 PresentedViewController 的警报 : "Attempt to present UIAlertController on ... whitch is already presenting UIAlertController"

Question

我正在尝试将 UIAlertController 中的推送通知(PN)中的消息从 AppDelegate 呈现到当前 ViewController。如果我发送 1 个 PN，没有问题，并且会显示警报!但是，在单击警报中的“确定”按钮之前，我发送了第二个 PN，该消息未显示并收到以下警告消息:

"Warning: Attempt to present <UIAlertController> on <NavigationViewController> which is already presenting <UIAlertController>"

那么我如何处理超过 1 个 PN 或者是否可以显示最后一个 PN？

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
        guard let aps = userInfo["aps"] as? [String: AnyObject] else {
            completionHandler(.failed)
            return
        }
        dump(aps)
        let message = aps["alert"] as? String
        let alertController = UIAlertController(title: "New message", message: message, preferredStyle: .alert)
        let ok = UIAlertAction(title: "OK", style: .default, handler: nil)
        alertController.addAction(ok)

        DispatchQueue.main.async {
            self.window?.rootViewController?.presentedViewController?.present(alertController, animated: true, completion: nil)
        }

        completionHandler(UIBackgroundFetchResult.noData)
}

Answer 1

您可以管理通知列表/堆栈并连续显示它们，直到您的列表/堆栈为空。

看看这个答案，了解如何显示多个警报:Attempt to present UIAlertController on View Controller which is already presenting (null) [Swift]