A UNNotificationContent object contains the data associated with a notification. When your app receives a notification, the associated UNNotificationRequest object contains an object of this type with the content that your app received. Use the content object to get the details of the notification, including the type of notification that was delivered, any custom data you stored in the userInfo dictionary before scheduling the notification, and any attachments.
Don't create instances of this class directly. For remote notifications, the contents of this object are derived from the JSON payload that your server sends to the APNS server. For local notifications, create a UNMutableNotificationContent object, and configure the contents of that object instead.