iOS 10 silent push notification not triggering backgrounded app

Question

I have an app in which I'm trying to receive and handle SILENT push notifications.

I'm registering for APNs as follows:

UNUserNotificationCenter.currentNotificationCenter().delegate = self
UNUserNotificationCenter.currentNotificationCenter().requestAuthorizationWithOptions([.Badge, .Sound, .Alert]) {(granted, error) in
    if granted {
        application.registerForRemoteNotifications()
    }
}

Implemented:

func userNotificationCenter(center: UNUserNotificationCenter, didReceiveNotificationResponse response: UNNotificationResponse, withCompletionHandler completionHandler: () -> Void) {
    // Handle notification
}

func userNotificationCenter(center: UNUserNotificationCenter, willPresentNotification notification: UNNotification, withCompletionHandler completionHandler: (UNNotificationPresentationOptions) -> Void) {
    // Handle notification
}

The app has UIBackgroundModes fetch and remote-notification

The APN content looks like:

{
    "aps":{
        "content-available":1,
        "badge":0
    },
    "action":"shareDelete",
    "shareId":633
}

When the app is in the foreground, userNotificationCenter(centre:withCompletionHandler:willPresentNotification) is fired when the notification is received, but when the app is backgrounded, nothing happens.

I can see the APN is received by changing the badge number, but nothing is triggered in app.

What am I missing?

(Also asked on Apple dev forums)

Answer 1

Method

func userNotificationCenter(center: UNUserNotificationCenter, didReceiveNotificationResponse response: UNNotificationResponse, withCompletionHandler completionHandler: () -> Void) {
    // Handle notification
}

called when user taps on notification or check it on Apple Watch:

Called to let your app know which action was selected by the user for a given notification.

You need to implement the old method

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {

}

Answer 2

UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];
center.delegate = self;
NSLog(@"%@",center.delegate);

Checkout if the center.detegate is still AppDelegate, in my case, it was changed to something like X****Delegate, so, willPresentNotification and didReceiveNotificationResponse were never called.

Answer 3

Are you setting minimumBackgroundFetchInterval? As mentioned in the docs:

The minimum number of seconds that must elapse before another background fetch can be initiated. This value is advisory only and does not indicate the exact amount of time expected between fetch operations.

The default fetch interval for apps is UIApplicationBackgroundFetchIntervalNever. Therefore, you must call this method and set a fetch interval before your app is given background execution time.

So if you're not setting this it's quite possible your fetch handler will never be called in the background.

Answer 4

When your application is in the background or not running the only way for your app to be notified is if the user select an action linked to to your notification.

See Local and remote notifications guide.

When your app is not running or is in the background, the system automatically delivers local and remote notifications using the interactions you specified. If the user selects an action, or chooses one of the standard interactions, the system notifies your app of the user’s selection. Your code can then use that selection to perform additional tasks. If your app is running in the foreground, notifications are delivered directly to your app. You can then decide whether to handle the notification quietly or alert the user.

To respond to the delivery of notifications, you must implement a delegate for the shared UNUserNotificationCenter object. Your delegate object must conform to the UNUserNotificationCenterDelegate protocol, which the notification center uses to deliver notification information to your app. A delegate is required if your notifications contain custom actions.

here is the source: https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/SchedulingandHandlingLocalNotifications.html#//apple_ref/doc/uid/TP40008194-CH5-SW14