How can I make UNNotificationRequest pop immediately?

Question

I'm working with UNNotificationRequest and I want that the notification popup immediately when I click on the button. but in this case it appears when I quit the application. Here's my code

@IBAction func shortNotifBtn(_ sender: Any) {
    let center = UNUserNotificationCenter.current()
    let content = UNMutableNotificationContent()
    content.title = "Late wake up call"
    content.body = "The early bird catches the worm, but the second mouse gets the cheese."
    content.categoryIdentifier = "alarm"
    content.userInfo = ["customData": "fizzbuzz"]
    content.sound = UNNotificationSound.default()
    let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 5, repeats: false)
    let request = UNNotificationRequest(identifier: UUID().uuidString, content: content, trigger: trigger)
    center.add(request)
}

Answer 1

Max's answer is for the deprecated UILocalNotification when the question is regarding the more modern UNNotificationRequest.

The correct answer is to pass nil along. According to the documentation for UNNotificationRequest's requestWithIdentifier:content:trigger:

trigger

The condition that causes the notification to be delivered. Specify nil to deliver the notification right away.

So in your code:

let request = UNNotificationRequest(identifier: UUID().uuidString, content: content, trigger: nil)