Add Core Data to an Existing SwiftUI Project

Create the Core Data model

In Xcode, choose File → New → File. Filter the file types by “data model,” select Data Model, and click Next. Keep the .xcdatamodeld extension and save the file.

Run the project without Core Data

Run the app in the simulator and add a TODO item. You can mark the task as complete, but after terminating and relaunching the app, the TODO items are gone because they are stored only in memory.

Next, you’ll configure the data model so those changes can persist.

Configure Model.xcdatamodeld

Select the Model.xcdatamodeld file you created, click Add Entity, and rename the entity to Todo.

Add two attributes to the Todo entity: taskName with type String, and isCompleted with type Boolean.

Update your DataManager

Open DataManager.swift, import CoreData, and create an NSPersistentContainer using the name of your model.

import CoreData
import Foundation

/// Main data manager to handle the todo items
class DataManager: NSObject, ObservableObject {
    @Published var todoItems: [TodoItem] = [TodoItem]()

    /// Core Data container using Model.xcdatamodeld
    let container: NSPersistentContainer = NSPersistentContainer(name: "Model")
}

Then load the persistent stores when the data manager is initialized.

import CoreData
import Foundation

class DataManager: NSObject, ObservableObject {
    @Published var todoItems: [TodoItem] = [TodoItem]()
    let container: NSPersistentContainer = NSPersistentContainer(name: "Model")

    override init() {
        super.init()
        container.loadPersistentStores { _, _ in }
    }
}

Inject the managed object context into SwiftUI

Open your @main application file and pass the Core Data container’s view context into the SwiftUI environment.

import SwiftUI

@main
struct TodoListApp: App {
    @StateObject private var manager: DataManager = DataManager()

    var body: some Scene {
        WindowGroup {
            ListContentView()
                .environmentObject(manager)
                .environment(\.managedObjectContext, manager.container.viewContext)
        }
    }
}

Add FetchRequest to the SwiftUI view

In ListContentView, access the managed object context and create a FetchRequest that loads Todo entities from Core Data.

import SwiftUI

struct ListContentView: View {
    @EnvironmentObject var manager: DataManager
    @Environment(\.managedObjectContext) private var viewContext
    @FetchRequest(sortDescriptors: []) private var todoItems: FetchedResults<Todo>

    // ...
}

Use FetchRequest data instead of DataManager

Replace the in-memory manager.todoItems collection with the todoItems FetchRequest. Core Data-backed changes will then update the SwiftUI view through the FetchRequest.

var body: some View {
    NavigationView {
        List {
            ForEach(todoItems) { item in
                Label(
                    item.taskName ?? "No Name",
                    systemImage: "circle\(item.isCompleted ? ".fill" : "")"
                )
                .frame(maxWidth: .infinity, alignment: .leading)
                .contentShape(Rectangle())
                .onTapGesture {
                    item.isCompleted = !item.isCompleted
                }
            }
        }
        .navigationTitle("TODO")
        .navigationBarItems(trailing: Button(action: addItem) {
            Image(systemName: "plus")
        })
    }
}

Save new items to Core Data

Update your existing addItem method so new tasks are created as Todo entities in the managed object context rather than being appended to the in-memory DataManager array.

private func addItem() {
    presentTextInputAlert(title: "Add Task", message: "Enter your task name") { name in
        let newTask = Todo(context: viewContext)
        newTask.taskName = name
        try? viewContext.save()
    }
}