Please help me. I designed an application and I was also able to send notifications to this application using onesignal. But I want the notifications to be saved inside the application and displayed on a special page. An example of this is the way notifications are displayed in the Facebook application and other applications.
Create a database Firebase if you like
When ever you send notifications using Onesignal go to Firebase and save the message you sent.
Then in you app you can design a page to show all the messages in Firebase.