For Each Detail View Data to Main View

Question

I don’t have any code for this, so I’ll make up a hypothetical situation:

I want to make a grocery list app. I have a tab bar that sends me to a view where I can create categories in a list (fruits, vegetables, dairy etc.) Each category sends the user to a detail view where they can list off certain brands and the amount they need.

(This is where it gets a bit tricky)

In the main view, the categories that the user made are now tabs that are on the bottom and the list they made in detail view appears on the screen. Any changes they make in the list shown (in the main view) will update back into the specific detail view.

Is that possible? And what technique would be used for something like this?