SwiftData @Model und ModelContext

Einführung in SwiftData

import SwiftData
// Main concepts: @Model, ModelContainer, ModelContext

@Model-Makro

@Model
class Item {
  var name: String
  var createdAt: Date
  init(name: String) {
    self.name = name
    self.createdAt = Date()
  }
}

ModelContainer einrichten

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

ModelContext in Views

struct AddItemView: View {
  @Environment(\.modelContext) private var context
  func addItem() {
    context.insert(Item(name: "New Item"))
  }
}

Einfügen und Löschen

let item = Item(name: "Coffee")
context.insert(item)   // add
context.delete(item)   // remove
// Auto-saved on next run loop

@Query zum Abrufen

struct ItemList: View {
  @Query(sort: \Item.createdAt, order: .reverse) var items: [Item]
  var body: some View {
    List(items) { item in Text(item.name) }
  }
}

Mit Prädikaten filtern

@Query(filter: #Predicate<Item> { $0.name.contains("Swift") })
var swiftItems: [Item]

Manuell speichern

do {
  try context.save()
} catch {
  print("Save error: \(error)")
}

@Attribute zur Anpassung

@Model
class User {
  @Attribute(.unique) var email: String
  @Attribute(.externalStorage) var avatar: Data?
  init(email: String) { self.email = email }
}

@Transient-Eigenschaften

@Model
class Session {
  var token: String
  @Transient var isExpired: Bool = false
  init(token: String) { self.token = token }
}

ModelContainer konfigurieren

let schema = Schema([Item.self, User.self])
let config = ModelConfiguration(schema: schema, isStoredInMemoryOnly: false)
let container = try ModelContainer(for: schema, configurations: config)

Kurze Überprüfung

Zusammenfassung der Lektion