SwiftDataDemo

WWDC23 introduces a new persistence Framework called SwiftData.

Note: All the code in this project and below was generated after selecting "SwiftData" as a Storage option.

Glossary

• .modelContainer(for: Item.self): sets the model container in the scene
• SwiftData: enables you to add persistence to your app quickly, with minimal code and no external dependencies
• @Model: converts a Swift class into a stored model that’s managed by SwiftData
• @Query private var items: [Item]: a property wrapper that fetches a set of models and keeps those models in sync with the underlying data
• @Environment(\.modelContext) private var modelContext: the SwiftData model context

Getting stated with SwiftData

• Create a new Xcode project using Xcode 15 Beta
• Select "SwiftData" as Storage
  
• Select to host in "CloudKit"
  
• After you've created your project the following files below will be populated with SwiftData boilerplate code.
• Create some "items" from the demo app and relaunch the simulator or device to verity that the items are being persisted.

SwiftDataDemoApp

import SwiftUI
import SwiftData

@main
struct SwiftDataDemoApp: App {

    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .modelContainer(for: Item.self)
    }
}

Item

import Foundation
import SwiftData

@Model
final class Item {
    var timestamp: Date
    
    init(timestamp: Date) {
        self.timestamp = timestamp
    }
}

ContentView

import SwiftUI
import SwiftData

struct ContentView: View {
    @Environment(\.modelContext) private var modelContext
    @Query private var items: [Item]
    
    var body: some View {
        NavigationView {
            List {
                ForEach(items) { item in
                    NavigationLink {
                        Text("Item at \(item.timestamp, format: Date.FormatStyle(date: .numeric, time: .standard))")
                    } label: {
                        Text(item.timestamp, format: Date.FormatStyle(date: .numeric, time: .standard))
                    }
                }
                .onDelete(perform: deleteItems)
            }
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    EditButton()
                }
                ToolbarItem {
                    Button(action: addItem) {
                        Label("Add Item", systemImage: "plus")
                    }
                }
            }
            Text("Select an item")
        }
    }

    private func addItem() {
        withAnimation {
            let newItem = Item(timestamp: Date())
            modelContext.insert(newItem)
        }
    }

    private func deleteItems(offsets: IndexSet) {
        withAnimation {
            for index in offsets {
                modelContext.delete(items[index])
            }
        }
    }
}

#Preview {
    ContentView()
        .modelContainer(for: Item.self, inMemory: true)
}

Resources

• Apple docs: SwiftData