Local push notification how get the payload

I implement the local push notification iOS from this example :

https://developer.apple.com/documentation/networkextension/local_push_connectivity/receiving_voice_and_text_communications_on_a_local_network

Everything works fine NEAppPushProvider intercept the message sended by the SimplePushServer but i want to develop my own server to push local notification what is the payload i must call to send notification to the ios application ? Any help will be appreciated