Migração de Core Data para SwiftData: Guia Passo a Passo 2026

Guia completo para migrar um aplicativo iOS de Core Data para SwiftData com exemplos práticos, estratégias de coexistência e boas práticas.

Guia de migração de Core Data para SwiftData para desenvolvedores iOS

SwiftData representa o futuro da persistência de dados nas plataformas Apple. Apresentado na WWDC 2023, esse framework oferece sintaxe Swift nativa e integração fluida com SwiftUI. Para aplicativos existentes baseados em Core Data, a migração constitui um passo estratégico rumo a um código mais moderno e fácil de manter.

O que este artigo aborda

Este guia detalha o processo completo de migração de Core Data para SwiftData: avaliação de compatibilidade, conversão de modelos, estratégias de migração de dados e padrões de coexistência para uma transição gradual.

Avaliação da Viabilidade da Migração

Antes de iniciar a migração, uma avaliação rigorosa permite identificar os possíveis obstáculos. Core Data e SwiftData compartilham o mesmo motor de persistência SQLite, o que torna os dados totalmente compatíveis.

MigrationAssessment.swiftswift
// Migration assessment checklist

/*
 FEATURES SUPPORTED BY SWIFTDATA:
 ✅ Simple models with basic properties
 ✅ One-to-one and one-to-many relationships
 ✅ Optional properties and default values
 ✅ Transformable attributes (via Codable)
 ✅ CloudKit synchronization (basic)
 ✅ Automatic lightweight migrations
 ✅ Class inheritance (iOS 26+)

 FEATURES REQUIRING ATTENTION:
 ⚠️ NSFetchedResultsController → @Query + manual observation
 ⚠️ NSCompoundPredicate → #Predicate with combined logic
 ⚠️ Dynamic predicates → Workarounds required

 UNSUPPORTED FEATURES:
 ❌ Advanced CloudKit Sharing
 ❌ Derived attributes
 ❌ Fetched properties
*/

// Example of typical Core Data model to migrate
import CoreData

// Existing Core Data entity
class CDTask: NSManagedObject {
    @NSManaged var id: UUID
    @NSManaged var title: String
    @NSManaged var isCompleted: Bool
    @NSManaged var createdAt: Date
    @NSManaged var priority: Int16
    @NSManaged var category: CDCategory?
}

class CDCategory: NSManagedObject {
    @NSManaged var id: UUID
    @NSManaged var name: String
    @NSManaged var color: String
    @NSManaged var tasks: NSSet?
}

A compatibilidade no nível dos dados garante que os usuários conservem suas informações existentes após a migração. Nenhuma perda de dados ocorre quando o processo é executado corretamente.

Conversão dos Modelos Core Data para SwiftData

O primeiro passo concreto consiste em converter as entidades Core Data em classes SwiftData. O Xcode oferece uma ferramenta automática, mas compreender o processo manual continua essencial.

TaskModel.swiftswift
import SwiftData

// SwiftData equivalent of CDTask
@Model
final class Task {
    // Properties with default values
    var id: UUID = UUID()
    var title: String = ""
    var isCompleted: Bool = false
    var createdAt: Date = Date()
    var priority: Int = 0

    // Optional relationship to Category
    var category: Category?

    // Explicit initializer recommended
    init(
        id: UUID = UUID(),
        title: String,
        isCompleted: Bool = false,
        createdAt: Date = Date(),
        priority: Int = 0,
        category: Category? = nil
    ) {
        self.id = id
        self.title = title
        self.isCompleted = isCompleted
        self.createdAt = createdAt
        self.priority = priority
        self.category = category
    }
}

As principais diferenças em relação ao Core Data incluem o uso da macro @Model em vez de NSManagedObject, além dos tipos Swift nativos no lugar de tipos Objective-C.

CategoryModel.swiftswift
import SwiftData

@Model
final class Category {
    var id: UUID = UUID()
    var name: String = ""
    var color: String = "blue"

    // Inverse relationship with delete rule
    @Relationship(deleteRule: .cascade, inverse: \Task.category)
    var tasks: [Task] = []

    init(id: UUID = UUID(), name: String, color: String = "blue") {
        self.id = id
        self.name = name
        self.color = color
    }
}
Mapeamento de tipos

Os tipos do Core Data convertem-se diretamente: Int16 torna-se Int, NSSet torna-se [Model] e Date permanece como Date. Os atributos Transformable exigem a adoção de Codable.

Configuração do ModelContainer

O ModelContainer do SwiftData substitui o NSPersistentContainer do Core Data. A configuração determina onde e como os dados são armazenados.

ModelContainerSetup.swiftswift
import SwiftData
import SwiftUI

@main
struct TaskManagerApp: App {
    // SwiftData container configuration
    var sharedModelContainer: ModelContainer = {
        // Schema including all models
        let schema = Schema([
            Task.self,
            Category.self
        ])

        // Configuration with storage options
        let modelConfiguration = ModelConfiguration(
            schema: schema,
            isStoredInMemoryOnly: false,
            // Use the same store as Core Data
            url: URL.applicationSupportDirectory
                .appending(path: "TaskManager.sqlite")
        )

        do {
            return try ModelContainer(
                for: schema,
                configurations: [modelConfiguration]
            )
        } catch {
            fatalError("Could not create ModelContainer: \(error)")
        }
    }()

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

O ponto crucial está na URL do store: usar o mesmo arquivo SQLite que o Core Data permite que o SwiftData leia os dados existentes.

Estratégia de Coexistência entre Core Data e SwiftData

Para aplicativos complexos, uma migração progressiva via coexistência dos dois frameworks representa a abordagem mais segura. Os dois stacks podem acessar o mesmo arquivo SQLite.

CoexistenceSetup.swiftswift
import CoreData
import SwiftData

// Configuration for coexistence
class PersistenceController {
    static let shared = PersistenceController()

    // Shared store between Core Data and SwiftData
    private let storeURL: URL = {
        let appSupport = FileManager.default
            .urls(for: .applicationSupportDirectory, in: .userDomainMask)
            .first!
        return appSupport.appending(path: "TaskManager.sqlite")
    }()

    // MARK: - Core Data Stack (existing)

    lazy var persistentContainer: NSPersistentContainer = {
        let container = NSPersistentContainer(name: "TaskManager")

        // Configure to use shared store
        let description = NSPersistentStoreDescription(url: storeURL)
        description.setOption(
            true as NSNumber,
            forKey: NSPersistentHistoryTrackingKey
        )
        container.persistentStoreDescriptions = [description]

        container.loadPersistentStores { _, error in
            if let error = error as NSError? {
                fatalError("Core Data error: \(error)")
            }
        }

        return container
    }()

    // MARK: - SwiftData Stack (new)

    lazy var swiftDataContainer: ModelContainer = {
        let schema = Schema([Task.self, Category.self])

        let config = ModelConfiguration(
            schema: schema,
            url: storeURL,
            // Disable automatic migrations in coexistence
            allowsSave: true
        )

        do {
            return try ModelContainer(for: schema, configurations: [config])
        } catch {
            fatalError("SwiftData error: \(error)")
        }
    }()
}
Sincronização das alterações

No modo de coexistência, as alterações feitas por um framework não ficam imediatamente visíveis para o outro. Pode ser necessário um reload explícito ou reinício do app.

Migração das Consultas: De NSFetchRequest para @Query

A diferença mais significativa diz respeito à forma de obter os dados. O SwiftUI utiliza o property wrapper @Query para substituir o @FetchRequest.

QueryMigration.swiftswift
import SwiftUI
import SwiftData

// ❌ Old pattern with Core Data
struct OldTaskListView: View {
    @FetchRequest(
        sortDescriptors: [
            NSSortDescriptor(keyPath: \CDTask.createdAt, ascending: false)
        ],
        predicate: NSPredicate(format: "isCompleted == NO")
    )
    private var tasks: FetchedResults<CDTask>

    var body: some View {
        List(tasks) { task in
            Text(task.title)
        }
    }
}

// ✅ New pattern with SwiftData
struct NewTaskListView: View {
    // @Query with built-in sorting and filtering
    @Query(
        filter: #Predicate<Task> { !$0.isCompleted },
        sort: \Task.createdAt,
        order: .reverse
    )
    private var tasks: [Task]

    var body: some View {
        List(tasks) { task in
            TaskRowView(task: task)
        }
    }
}

struct TaskRowView: View {
    let task: Task

    var body: some View {
        HStack {
            // Priority indicator
            Circle()
                .fill(priorityColor)
                .frame(width: 8, height: 8)

            VStack(alignment: .leading) {
                Text(task.title)
                    .font(.headline)

                if let category = task.category {
                    Text(category.name)
                        .font(.caption)
                        .foregroundStyle(.secondary)
                }
            }

            Spacer()

            // Date badge
            Text(task.createdAt, style: .date)
                .font(.caption2)
                .foregroundStyle(.tertiary)
        }
    }

    private var priorityColor: Color {
        switch task.priority {
        case 3: return .red
        case 2: return .orange
        case 1: return .yellow
        default: return .gray
        }
    }
}

Pronto para mandar bem nas entrevistas de iOS?

Pratique com nossos simuladores interativos, flashcards e testes tecnicos.

Tratamento de Predicados Dinâmicos

Um grande desafio com o SwiftData diz respeito aos predicados dinâmicos. Diferentemente do Core Data, em que os predicados podem ser modificados em tempo real, o @Query exige abordagens alternativas.

DynamicPredicates.swiftswift
import SwiftUI
import SwiftData

// Solution 1: Use @Query with custom init
struct FilteredTasksView: View {
    @Query private var tasks: [Task]

    // Create view with specific filter
    init(showCompleted: Bool, categoryId: UUID?) {
        // Build predicate based on parameters
        var predicates: [Predicate<Task>] = []

        if !showCompleted {
            predicates.append(#Predicate { !$0.isCompleted })
        }

        if let categoryId {
            predicates.append(#Predicate { task in
                task.category?.id == categoryId
            })
        }

        // Combine predicates
        let combinedPredicate: Predicate<Task>?
        if predicates.isEmpty {
            combinedPredicate = nil
        } else if predicates.count == 1 {
            combinedPredicate = predicates[0]
        } else {
            // Manually combine for AND logic
            combinedPredicate = #Predicate<Task> { task in
                !task.isCompleted && task.category?.id == categoryId
            }
        }

        _tasks = Query(
            filter: combinedPredicate,
            sort: \Task.createdAt,
            order: .reverse
        )
    }

    var body: some View {
        List(tasks) { task in
            TaskRowView(task: task)
        }
    }
}

// Solution 2: View-side filtering with all results
struct SmartTaskListView: View {
    // Fetch all tasks
    @Query(sort: \Task.createdAt, order: .reverse)
    private var allTasks: [Task]

    // Filter state
    @State private var searchText = ""
    @State private var showCompleted = false
    @State private var selectedCategory: Category?

    // Computed filtering
    private var filteredTasks: [Task] {
        allTasks.filter { task in
            // Text filter
            let matchesSearch = searchText.isEmpty ||
                task.title.localizedCaseInsensitiveContains(searchText)

            // Status filter
            let matchesStatus = showCompleted || !task.isCompleted

            // Category filter
            let matchesCategory = selectedCategory == nil ||
                task.category?.id == selectedCategory?.id

            return matchesSearch && matchesStatus && matchesCategory
        }
    }

    var body: some View {
        NavigationStack {
            List(filteredTasks) { task in
                TaskRowView(task: task)
            }
            .searchable(text: $searchText)
            .toolbar {
                FilterMenu(
                    showCompleted: $showCompleted,
                    selectedCategory: $selectedCategory
                )
            }
        }
    }
}

Migrações de Schema Versionadas

Quando o modelo de dados evolui, o SwiftData utiliza VersionedSchema para gerenciar migrações complexas.

VersionedSchemas.swiftswift
import SwiftData

// Version 1: Initial schema
enum TaskSchemaV1: VersionedSchema {
    static var versionIdentifier = Schema.Version(1, 0, 0)

    static var models: [any PersistentModel.Type] {
        [Task.self, Category.self]
    }

    @Model
    final class Task {
        var id: UUID = UUID()
        var title: String = ""
        var isCompleted: Bool = false
        var createdAt: Date = Date()
        var category: Category?

        init(title: String) {
            self.title = title
        }
    }

    @Model
    final class Category {
        var id: UUID = UUID()
        var name: String = ""

        @Relationship(deleteRule: .cascade, inverse: \Task.category)
        var tasks: [Task] = []

        init(name: String) {
            self.name = name
        }
    }
}

// Version 2: Added priority and notes fields
enum TaskSchemaV2: VersionedSchema {
    static var versionIdentifier = Schema.Version(2, 0, 0)

    static var models: [any PersistentModel.Type] {
        [Task.self, Category.self]
    }

    @Model
    final class Task {
        var id: UUID = UUID()
        var title: String = ""
        var isCompleted: Bool = false
        var createdAt: Date = Date()
        // New properties with default values
        var priority: Int = 0
        var notes: String = ""
        var category: Category?

        init(title: String, priority: Int = 0) {
            self.title = title
            self.priority = priority
        }
    }

    @Model
    final class Category {
        var id: UUID = UUID()
        var name: String = ""
        // New property
        var color: String = "blue"

        @Relationship(deleteRule: .cascade, inverse: \Task.category)
        var tasks: [Task] = []

        init(name: String, color: String = "blue") {
            self.name = name
            self.color = color
        }
    }
}

O plano de migração define a ordem das versões e eventuais migrações personalizadas necessárias.

MigrationPlan.swiftswift
import SwiftData

enum TaskMigrationPlan: SchemaMigrationPlan {
    // Chronological order of schemas
    static var schemas: [any VersionedSchema.Type] {
        [TaskSchemaV1.self, TaskSchemaV2.self]
    }

    // Migration stages
    static var stages: [MigrationStage] {
        [migrateV1toV2]
    }

    // V1 → V2 migration: lightweight (properties with defaults)
    static let migrateV1toV2 = MigrationStage.lightweight(
        fromVersion: TaskSchemaV1.self,
        toVersion: TaskSchemaV2.self
    )
}

// Container configuration with migration
@main
struct TaskManagerApp: App {
    var sharedModelContainer: ModelContainer = {
        do {
            return try ModelContainer(
                for: TaskSchemaV2.Task.self, TaskSchemaV2.Category.self,
                migrationPlan: TaskMigrationPlan.self
            )
        } catch {
            fatalError("Migration failed: \(error)")
        }
    }()

    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .modelContainer(sharedModelContainer)
    }
}
Migrações lightweight vs personalizadas

O SwiftData lida automaticamente com migrações lightweight (adicionar propriedades com valores padrão, renomear, excluir). Migrações complexas que exigem transformação de dados utilizam MigrationStage.custom.

Substituição de NSFetchedResultsController

Para listas com seções ou observação detalhada de mudanças, o @Query combinado com extração de dados substitui o NSFetchedResultsController.

SectionedResults.swiftswift
import SwiftUI
import SwiftData

struct SectionedTaskListView: View {
    @Query(sort: \Task.createdAt, order: .reverse)
    private var tasks: [Task]

    // Grouping by category
    private var tasksByCategory: [(Category?, [Task])] {
        Dictionary(grouping: tasks) { $0.category }
            .map { ($0.key, $0.value) }
            .sorted { first, second in
                // Tasks without category last
                guard let firstName = first.0?.name else { return false }
                guard let secondName = second.0?.name else { return true }
                return firstName < secondName
            }
    }

    var body: some View {
        List {
            ForEach(tasksByCategory, id: \.0?.id) { category, categoryTasks in
                Section(header: SectionHeader(category: category)) {
                    ForEach(categoryTasks) { task in
                        TaskRowView(task: task)
                    }
                }
            }
        }
    }
}

struct SectionHeader: View {
    let category: Category?

    var body: some View {
        HStack {
            if let category {
                Circle()
                    .fill(Color(category.color))
                    .frame(width: 12, height: 12)
                Text(category.name)
            } else {
                Text("Uncategorized")
                    .foregroundStyle(.secondary)
            }
        }
    }
}

// Alternative: Grouping by date
struct DateGroupedTasksView: View {
    @Query(sort: \Task.createdAt, order: .reverse)
    private var tasks: [Task]

    private var tasksByDate: [(Date, [Task])] {
        let calendar = Calendar.current

        let grouped = Dictionary(grouping: tasks) { task in
            calendar.startOfDay(for: task.createdAt)
        }

        return grouped
            .map { ($0.key, $0.value) }
            .sorted { $0.0 > $1.0 }
    }

    var body: some View {
        List {
            ForEach(tasksByDate, id: \.0) { date, dateTasks in
                Section(header: Text(date, style: .date)) {
                    ForEach(dateTasks) { task in
                        TaskRowView(task: task)
                    }
                }
            }
        }
    }
}

Operações CRUD com ModelContext

O ModelContext substitui o NSManagedObjectContext em todas as operações de criação, leitura, atualização e exclusão.

CRUDOperations.swiftswift
import SwiftUI
import SwiftData

struct TaskManagementView: View {
    @Environment(\.modelContext) private var modelContext
    @Query private var tasks: [Task]
    @Query private var categories: [Category]

    @State private var newTaskTitle = ""
    @State private var selectedCategory: Category?

    var body: some View {
        NavigationStack {
            VStack {
                // Add form
                AddTaskForm(
                    title: $newTaskTitle,
                    category: $selectedCategory,
                    categories: categories,
                    onAdd: addTask
                )

                // Task list
                List {
                    ForEach(tasks) { task in
                        TaskRowView(task: task)
                            .swipeActions(edge: .trailing) {
                                Button(role: .destructive) {
                                    deleteTask(task)
                                } label: {
                                    Label("Delete", systemImage: "trash")
                                }
                            }
                            .swipeActions(edge: .leading) {
                                Button {
                                    toggleCompletion(task)
                                } label: {
                                    Label(
                                        task.isCompleted ? "Todo" : "Done",
                                        systemImage: task.isCompleted ? "circle" : "checkmark"
                                    )
                                }
                                .tint(task.isCompleted ? .orange : .green)
                            }
                    }
                }
            }
            .navigationTitle("Tasks")
        }
    }

    // CREATE
    private func addTask() {
        guard !newTaskTitle.isEmpty else { return }

        let task = Task(
            title: newTaskTitle,
            category: selectedCategory
        )

        // Insert into context
        modelContext.insert(task)

        // Explicit save (optional - autosave enabled by default)
        do {
            try modelContext.save()
        } catch {
            print("Save error: \(error)")
        }

        // Reset form
        newTaskTitle = ""
        selectedCategory = nil
    }

    // UPDATE
    private func toggleCompletion(_ task: Task) {
        // Direct modification - SwiftData tracks automatically
        task.isCompleted.toggle()

        // Automatic save handles persistence
    }

    // DELETE
    private func deleteTask(_ task: Task) {
        modelContext.delete(task)
    }
}

struct AddTaskForm: View {
    @Binding var title: String
    @Binding var category: Category?
    let categories: [Category]
    let onAdd: () -> Void

    var body: some View {
        VStack(spacing: 12) {
            TextField("New task...", text: $title)
                .textFieldStyle(.roundedBorder)

            HStack {
                Picker("Category", selection: $category) {
                    Text("None").tag(nil as Category?)
                    ForEach(categories) { cat in
                        Text(cat.name).tag(cat as Category?)
                    }
                }
                .pickerStyle(.menu)

                Button("Add", action: onAdd)
                    .buttonStyle(.borderedProminent)
                    .disabled(title.isEmpty)
            }
        }
        .padding()
    }
}

Testes Unitários com SwiftData

Uma estratégia de testes robusta facilita a validação da migração. O SwiftData permite criar contêineres em memória para os testes.

SwiftDataTests.swiftswift
import XCTest
import SwiftData
@testable import TaskManager

final class TaskModelTests: XCTestCase {
    var container: ModelContainer!
    var context: ModelContext!

    override func setUpWithError() throws {
        // In-memory container for tests
        let config = ModelConfiguration(isStoredInMemoryOnly: true)
        container = try ModelContainer(
            for: Task.self, Category.self,
            configurations: config
        )
        context = ModelContext(container)
    }

    override func tearDownWithError() throws {
        container = nil
        context = nil
    }

    func testCreateTask() throws {
        // Given
        let task = Task(title: "Test Task")

        // When
        context.insert(task)
        try context.save()

        // Then
        let descriptor = FetchDescriptor<Task>()
        let tasks = try context.fetch(descriptor)

        XCTAssertEqual(tasks.count, 1)
        XCTAssertEqual(tasks.first?.title, "Test Task")
    }

    func testTaskCategoryRelationship() throws {
        // Given
        let category = Category(name: "Work", color: "blue")
        let task = Task(title: "Meeting", category: category)

        // When
        context.insert(category)
        context.insert(task)
        try context.save()

        // Then
        XCTAssertEqual(task.category?.name, "Work")
        XCTAssertTrue(category.tasks.contains(task))
    }

    func testDeleteCategoryCascade() throws {
        // Given
        let category = Category(name: "Personal")
        let task1 = Task(title: "Task 1", category: category)
        let task2 = Task(title: "Task 2", category: category)

        context.insert(category)
        context.insert(task1)
        context.insert(task2)
        try context.save()

        // When
        context.delete(category)
        try context.save()

        // Then - cascade delete should remove tasks
        let descriptor = FetchDescriptor<Task>()
        let remainingTasks = try context.fetch(descriptor)

        XCTAssertEqual(remainingTasks.count, 0)
    }

    func testFilteredFetch() throws {
        // Given
        let task1 = Task(title: "Completed", isCompleted: true)
        let task2 = Task(title: "Pending", isCompleted: false)
        let task3 = Task(title: "Also Pending", isCompleted: false)

        [task1, task2, task3].forEach { context.insert($0) }
        try context.save()

        // When
        var descriptor = FetchDescriptor<Task>(
            predicate: #Predicate { !$0.isCompleted }
        )
        let pendingTasks = try context.fetch(descriptor)

        // Then
        XCTAssertEqual(pendingTasks.count, 2)
    }
}

Checklist Completo de Migração

Abaixo, um resumo das etapas para uma migração bem-sucedida:

MigrationChecklist.swiftswift
/*
 PHASE 1: PREPARATION
 □ Audit Core Data features in use
 □ Identify features not supported by SwiftData
 □ Create dedicated migration branch
 □ Back up test data

 PHASE 2: MODEL CONVERSION
 □ Convert NSManagedObject entities to @Model
 □ Adapt relationships with @Relationship
 □ Configure appropriate delete rules
 □ Add required default values

 PHASE 3: CONFIGURATION
 □ Create ModelContainer with existing store URL
 □ Configure versioned schema if needed
 □ Define migration plan
 □ Test in coexistence mode if applicable

 PHASE 4: CODE MIGRATION
 □ Replace @FetchRequest with @Query
 □ Adapt predicates to #Predicate
 □ Migrate NSFetchedResultsController to manual grouping
 □ Convert CRUD operations to ModelContext

 PHASE 5: VALIDATION
 □ Run all unit tests
 □ Test migration with real data
 □ Verify performance with Instruments
 □ Validate CloudKit sync (if applicable)

 PHASE 6: DEPLOYMENT
 □ Document breaking changes
 □ Prepare rollback plan
 □ Deploy to TestFlight
 □ Monitor post-deployment crashes
*/

Conclusão

A migração de Core Data para SwiftData representa uma evolução natural para os aplicativos iOS modernos. A compatibilidade no nível do store SQLite garante a preservação dos dados do usuário, enquanto a sintaxe Swift nativa simplifica consideravelmente o código.

Pontos-Chave

  • ✅ SwiftData e Core Data compartilham o mesmo motor SQLite
  • ✅ A coexistência permite uma migração gradual
  • @Query substitui @FetchRequest com sintaxe mais simples
  • ✅ Predicados dinâmicos exigem padrões alternativos
  • VersionedSchema gerencia a evolução do schema
  • ✅ Testes em memória facilitam a validação
  • ✅ iOS 26 traz suporte à herança de classes
  • ✅ Convém iniciar novos projetos com SwiftData, salvo necessidades específicas do Core Data

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Tags

#swiftdata
#core-data
#ios
#migration
#swift

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