swiftui-data

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Implement data persistence with SwiftData, Core Data, CloudKit sync, and local storage. Use when storing app data, creating database models, syncing with iCloud, or managing user preferences with AppStorage.

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[Code Generation]

When & Why to Use This Skill

This Claude skill provides comprehensive implementation patterns for data persistence in SwiftUI applications. It streamlines the integration of modern SwiftData (iOS 17+), legacy Core Data, and CloudKit synchronization, enabling developers to build robust, data-driven iOS apps. By offering optimized code snippets for data modeling, CRUD operations, and user preference management, it ensures best practices in local storage and cloud-based data consistency.

Use Cases

  • case 1: Implementing local data persistence and complex relationship modeling in modern iOS apps using SwiftData.
  • case 2: Enabling seamless cross-device data synchronization via CloudKit for users within the Apple ecosystem.
  • case 3: Managing lightweight user settings and UI state persistence using @AppStorage and @SceneStorage for a better user experience.
  • case 4: Architecting data-heavy applications that require efficient querying, filtering, and sorting of local database records.
nameswiftui-data
descriptionImplement data persistence with SwiftData, Core Data, CloudKit sync, and local storage. Use when storing app data, creating database models, syncing with iCloud, or managing user preferences with AppStorage.

SwiftUI Data Persistence

SwiftData (iOS 17+) - Recommended

import SwiftData

@Model
final class Task {
    var title: String
    var isCompleted: Bool
    var createdAt: Date
    var priority: Priority

    @Relationship(deleteRule: .cascade)
    var subtasks: [Subtask]?

    init(title: String, priority: Priority = .medium) {
        self.title = title
        self.isCompleted = false
        self.createdAt = .now
        self.priority = priority
    }
}

enum Priority: String, Codable, CaseIterable {
    case low, medium, high
}

// App configuration
@main
struct MyApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .modelContainer(for: Task.self)
    }
}

SwiftData Queries

struct TaskListView: View {
    @Query(
        filter: #Predicate<Task> { !$0.isCompleted },
        sort: \Task.createdAt,
        order: .reverse
    )
    private var tasks: [Task]

    @Environment(\.modelContext) private var context

    var body: some View {
        List(tasks) { task in
            TaskRow(task: task)
                .swipeActions {
                    Button("Delete", role: .destructive) {
                        context.delete(task)
                    }
                }
        }
    }

    func addTask(_ title: String) {
        let task = Task(title: title)
        context.insert(task)
    }
}

CloudKit Sync with SwiftData

// Enable in App configuration
@main
struct MyApp: App {
    var container: ModelContainer

    init() {
        let schema = Schema([Task.self, Subtask.self])
        let config = ModelConfiguration(
            schema: schema,
            cloudKitDatabase: .private("iCloud.com.myapp")
        )
        container = try! ModelContainer(
            for: schema,
            configurations: [config]
        )
    }

    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .modelContainer(container)
    }
}

AppStorage & SceneStorage

struct SettingsView: View {
    // Persists to UserDefaults
    @AppStorage("username") private var username = ""
    @AppStorage("isDarkMode") private var isDarkMode = false
    @AppStorage("fontSize") private var fontSize = 14.0

    // Persists per-scene (window state)
    @SceneStorage("selectedTab") private var selectedTab = 0

    var body: some View {
        Form {
            TextField("Username", text: $username)
            Toggle("Dark Mode", isOn: $isDarkMode)
            Slider(value: $fontSize, in: 10...24)
        }
    }
}

When to Use What

Solution Use Case
@AppStorage Simple preferences, settings
@SceneStorage Window/scene-specific UI state
SwiftData Complex models, relationships, CloudKit
Core Data iOS < 17, advanced migrations
Keychain Sensitive data (tokens, passwords)
FileManager Documents, large files, exports