因此，我一直在尝试向新的UNUserNotificationCenter添加通知，但似乎没有收到。

我的视图控制器有一个动作：

@IBAction func sendPressed(_ sender: AnyObject) {
    let content = UNMutableNotificationContent()

    content.title = "Hello"
    content.body = "What up?"
    content.sound = UNNotificationSound.default()

    // Deliver the notification in five seconds.
    let trigger = UNTimeIntervalNotificationTrigger.init(timeInterval: 5, repeats: false)
    let request = UNNotificationRequest.init(identifier: "FiveSecond", content: content, trigger: trigger)

    // Schedule the notification.
    let center = UNUserNotificationCenter.current()
    center.add(request) { (error) in
        print(error)
    }
    print("should have been added")
}

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    let center = UNUserNotificationCenter.current()
    center.requestAuthorization([.alert, .sound]) { (granted, error) in
    }
}

而且我Notification Content Extension在项目中也有一个，但是它似乎根本没有被触发，我缺少什么主意？我正在尝试用户文档中的示例，但并没有告诉我更多信息，或者我错过了它。

此处：https
:
//developer.apple.com/reference/usernotifications/unmutablenotificationcontent

另外：https :
//developer.apple.com/reference/usernotificationsui
https://developer.apple.com/reference/usernotifications

编辑：

因此，将应用程序置于后台就可以了。