Why is my local notifications not triggered in the foreground in iOS 10?

Question

I'm trying to understand why the local notifications is not being displayed in the foreground. I believe I added all the correct code to allow this ability but no banner is showing when my app is in the foreground.

Here's what I added in AppDelegate.swift:

import UserNotifications

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate
{
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool
    {
        UNUserNotificationCenter.current().requestAuthorization(options: [UNAuthorizationOptions.alert, UNAuthorizationOptions.sound, UNAuthorizationOptions.badge]) { (willAllow: Bool, error: Error?) in

            if willAllow == true
            {
                // Do something
            }

        }

        UNUserNotificationCenter.current().delegate = self

        // Override point for customization after application launch.
        return true
    }

    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void)
    {
        print("GO IN HERE")
        completionHandler(.alert)
    }

    func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void)
    {

    }

}

My ViewController.swift:

override func viewDidLoad()
{
    super.viewDidLoad()

    let content: UNMutableNotificationContent = UNMutableNotificationContent()
    content.sound = UNNotificationSound.default()
    content.subtitle = "This is a test"

    let trigger: UNTimeIntervalNotificationTrigger = UNTimeIntervalNotificationTrigger(timeInterval: 5, repeats: false)

    let request: UNNotificationRequest = UNNotificationRequest(identifier: "timerDone", content: content, trigger: trigger)

    UNUserNotificationCenter.current().add(request, withCompletionHandler: nil)
}

When my app launches for the first time, I do see a permissions alert to allow my app to push notifications, but I don't see any notifications at all.

I do see the log output GO IN HERE, so willPresent is being called.

Is there something else that I'm missing?

Answer 1

In reference to the following answer: UserNotification is not showing (iOS 10)

The reason why my local notifications was not presented in the foreground is not because I "will never see the notifications in the foreground" as mentioned by the previous answer, but because I'm required to set at least the body content, and I did not set that in my code.

By setting content.body = "Some message", I can finally see the notification in the foreground while my app is running.