Deliver notifications that wake your app and update it in the background.
If your app’s server-based content changes infrequently or at irregular intervals, you can use background notifications to notify your app when new content becomes available. A background notification is a remote notification that doesn’t display an alert, play a sound, or badge your app’s icon. It wakes your app in the background and gives it time to initiate downloads from your server and update its content.
Enable the Remote Notifications Capability
To receive background notifications, your app must support the remote notifications background mode. You configure this mode in the Capabilities tab of your project, as shown in Figure 1.
Create a Background Notification
To send a background notification, create a remote notification with an
aps dictionary that includes only the
content-available key, as shown in Listing 1. You may include custom keys in the payload, but the
aps dictionary must not contain any keys that would trigger user interactions.
Additionally, the notification’s POST request should contain the
apns-push-type header field, with a value of
background. The APNs server requires this header field when sending push notifications to Apple Watch, and recommends it for all platforms. For more information, see Create and Send a POST Request to APNs.
When a device receives a background notification, the system wakes your app in the background. On iOS it calls your app delegate’s
application(_: method. On watchOS, it calls your extension delegate’s
did method. Your app has 30 seconds to perform any tasks and call the provided completion handler. For more information, see Handling Notifications and Notification-Related Actions.