This is how to setup core data with in memory option and complete file protection

CoreDataFileProtection.swift

import CoreData

class DataController {
    let container: NSPersistentContainer
  
    /// Core Data initialization
    /// - Parameter inMemory: For testing and previewing purposes, we create a temporary,
    /// in-memory database by writing to /dev/null so our data is destroyed after our data finishes running.
    init(inMemory: Bool = false) {
        container = NSPersistentContainer(name: "Main")
        
        if inMemory {
            container.persistentStoreDescriptions.first?.url = URL(filePath: "/dev/null")
        }
        
        // Setup complete file protection for container
        container.persistentStoreDescriptions.first?.setOption(FileProtectionType.complete as NSObject, forKey: NSPersistentStoreFileProtectionKey)
        
        container.loadPersistentStores { storeDescription, error in
            if let error {
                fatalError("Error loading CoreData store: \(error.localizedDescription)")
            }
        }
    }
}