Optional
threadOptional
categoryDefine your own iOS rich text push type and parse it in your app. Use it with richMediaUri. When you set the category, the push includes mutable-content by default, with a value of 1. If not set, the backend defaults to the message type string, like RC:TxtMsg.
Optional
apnsWhen apnsCollapseId matches, new notifications replace old ones on iOS. Max 64 bytes, supported since iOS 10.
Optional
richURL for iOS rich notification content, used with category.
Group notifications with the same thread-id in iOS notification center, supported since iOS 10