ax-swiftdata

SwiftData

Quick Patterns

@Model Definition

@Model
final class Track {
    @Attribute(.unique) var id: UUID
    var title: String
    var artist: String
    var duration: TimeInterval
    var playCount: Int = 0

    // Relationships
    @Relationship(deleteRule: .cascade, inverse: \Playlist.tracks)
    var playlists: [Playlist] = []

    // Transient (not persisted)
    @Transient var isPlaying: Bool = false

    // Indexes for query performance
    static let indexes: [[IndexColumn<Track>]] = [
        [.init(\.artist), .init(\.title)]
    ]

    init(id: UUID = UUID(), title: String, artist: String, duration: TimeInterval) {
        self.id = id
        self.title = title
        self.artist = artist
        self.duration = duration
    }
}

ModelContainer Setup

// Basic
let container = try ModelContainer(for: Track.self, Playlist.self)

// With configuration
let config = ModelConfiguration(
    "MyStore",
    schema: Schema([Track.self, Playlist.self]),
    isStoredInMemoryOnly: false,
    allowsSave: true,
    cloudKitDatabase: .private("iCloud.com.app.id")
)
let container = try ModelContainer(
    for: Track.self, Playlist.self,
    configurations: config
)

// SwiftUI
@main
struct MyApp: App {
    var body: some Scene {
        WindowGroup { ContentView() }
            .modelContainer(for: [Track.self, Playlist.self])
    }
}

@Query in SwiftUI

struct TrackListView: View {
    @Query(
        filter: #Predicate<Track> { $0.playCount > 0 },
        sort: [SortDescriptor(\.title)],
        animation: .default
    ) private var tracks: [Track]

    @Environment(\.modelContext) private var context

    var body: some View {
        List(tracks) { track in
            Text(track.title)
        }
    }
}

CRUD Operations

// Create
let track = Track(title: "Song", artist: "Artist", duration: 210)
context.insert(track)

// Read
let descriptor = FetchDescriptor<Track>(
    predicate: #Predicate { $0.artist == "Artist" },
    sortBy: [SortDescriptor(\.title)]
)
descriptor.fetchLimit = 20
let tracks = try context.fetch(descriptor)

// Update
track.playCount += 1
// Auto-saved by context

// Delete
context.delete(track)

// Batch delete
try context.delete(model: Track.self, where: #Predicate { $0.playCount == 0 })

// Save explicitly
try context.save()