As defined by Apple documentation, push notifications can contain custom data in the payload: https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/CreatingtheNotificationPayload.html#//apple_ref/doc/uid/TP40008194-CH10-SW1 Since PushNotificationHandler only passes `aps` data to the subscribers, custom data cannot be accessed. https://github.com/gtsifrikas/PushNotificationHandler/blob/master/PushNotificationHandler/PushNotificationHandler.swift#L84