rawContent

The raw, JSON-formatted string to use as the payload for the notification message. If specified, this value overrides all other content for the message.

If you specify the raw content of an APNs push notification, the message payload has to include the content-available key. The value of the content-available key has to be an integer, and can only be 0 or 1. If you're sending a standard notification, set the value of content-available to 0. If you're sending a silent (background) notification, set the value of content-available to 1. Additionally, silent notification payloads can't include the alert, badge, or sound keys. For more information, see Generating a Remote Notification and Pushing Background Updates to Your App on the Apple Developer website.