CloudKit CKSubscription without notifications? - ios

Question

I'm writing a Swift app with CloudKit. When a record is modified in CloudKit by a device, I want the corresponding records to be updated in the local storage of the other devices without displaying a push notification.
Do I need to call registerUserNotificationSettings in didFinishLaunchingWithOptions (meaning that the user has to accept the notifications for my app) even if I don't plan to display any push notification?
application.registerUserNotificationSettings(UIUserNotificationSettings(forTypes: .Alert, categories: nil))

Answer 1

In this case you do not need to call registerUserNotificationSettings.
You need to add the Info.plist setting "Required background mode" (UIBackgroundModes), "App downloads content in response to push notifications" (remote-notification). And also call registerForRemoteNotifications. Finally, set notificationInfo.shouldSendContentAvailable = YES; on your subscription.
Now since your app is being run to respond to all notifications you need to be careful to handle the case where a notification is missed, you can use airplane mode to test that, only the last is delivered.
Note, once you have created your subscription from any device, application:didReceiveRemoteNotification:fetchCompletionHandler: will be called on all devices that are using the same iCloud account and have the app installed.

Answer 2

Yes you do need to call registerUserNotificationSettings even all you need is background remote notification. So user will be prompt for notifications permission. It makes no sense as users will not be seeing the notifications but that's how it is.
I use this to set it up:
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
let settings = UIUserNotificationSettings(forTypes: .None , categories: nil)
application.registerUserNotificationSettings(settings)
application.registerForRemoteNotifications()
}
Make sure when you call CloudKit saveSubscription you provide shouldSendContentAvailable = true. The following code is for subscription for a custom zone:
let subscription = CKSubscription(zoneID:zoneID, options: CKSubscriptionOptions(rawValue: 0))
let notificationInfo = CKNotificationInfo()
notificationInfo.shouldSendContentAvailable = true
subscription.notificationInfo = notificationInfo
CKContainer.defaultContainer().privateCloudDatabase.saveSubscription(subscription) { subscription, error in
}
You also need to enable Background Modes capability under Xcode for your project, and tick the box Remote Notifications.
User can go to Settings app to disable notifications for your app. But you will still receive remote notification trigger by CloudKit server.
Implement the following functions in your AppDelegate to receive remote notifications:
func application(application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: NSData) {}
func application(application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: NSError) {}
func application(application: UIApplication, didReceiveRemoteNotification userInfo: [NSObject : AnyObject]) {}