Create a UNMutableNotificationContent object when you want to specify the payload for a local notification. Specifically, use this object to specify the title and message for an alert, the sound to play, or the value to assign to your app's badge. You might also provide details about how the system handles the notification. For example, you can specify a custom launch image and a thread identifier for visually grouping related notifications.
After creating your content object, assign it to a UNNotificationRequest object, add a trigger condition, and schedule your notification. The trigger condition defines when the notification is delivered to the user. Listing 1 shows the scheduling of a local notification that displays an alert and plays a sound after a delay of five seconds. The strings for the alert's title and body are stored in the app’s Localizable.strings file.
Localizing the Alert Strings
The strings you display in a notification alert should be localized for the current user. Although you can use the NSLocalizedString macros to load strings from your app’s resource files, a better option is to specify your string using the localizedUserNotificationStringForKey:arguments: method of NSString. The localizedUserNotificationStringForKey:arguments: method delays the loading of the localized string until the notification is delivered. Thus, if the user changes language settings before a notification is delivered, the alert text is updated to the user’s current language instead of the language that was set when the notification was scheduled.