I am developing an app using SwiftUI and Swift. I have a Firebase database with the following structure:

Collection named products,
Documents representing countries,
Subcollections representing districts,
Documents representing cities,
Subcollections containing various documents.
Given this structure, how can I retrieve all documents from a specific district, noting that a district contains multiple cities, each with its own set of documents?

Any code examples or explanations on how to achieve this in Swift would be greatly appreciated.