SwiftData Basics

SwiftData (iOS 17+) is Apple's modern, code-first persistence framework. You'll define models with @Model , set up a ModelContainer , fetch with @Query , insert and delete objects, and see how it improves on Core Data.

Learn SwiftData Basics in our free Swift course — a beginner-friendly interactive lesson with worked examples, a practice exercise and a quick reference.

Part of the free Swift course at LearnCodingFast — hands-on lessons with examples you run in your browser, plus practice exercises and a quick quiz.

What You'll Learn in This Lesson

• • Define a persistent model with the @Model macro
• • Configure storage with a ModelContainer
• • Fetch and observe data using @Query
• • Insert and delete objects via the ModelContext
• • Read the context from the SwiftUI environment
• • Compare SwiftData with Core Data (iOS 17+)

📊 SwiftData Building Blocks

Piece

Role

@Model

Makes a class persistent

ModelContainer

Sets up storage

ModelContext

Insert / delete workspace

@Query

Fetch and observe models

1️⃣ Define a Model with @Model

A SwiftData model is just a class with the @Model macro. The macro adds persistence and change tracking — no separate model file, no setValue(forKey:) .

2️⃣ Set Up the Container

Attach a ModelContainer once at the app root with .modelContainer(for:) . Views then read the active ModelContext from the environment.

Your turn. Fill in the macro and the model type.

3️⃣ Query, Insert, and Delete

@Query fetches models with type-safe sorting and keeps the view in sync. Use context.insert(_:) to add and context.delete(_:) to remove.

Now you try. Fill in the insert and delete methods.

Pro Tips

• 💡 List every model type in .modelContainer(for:) or it won't be stored.
• 💡 Sort with key paths, e.g. @Query(sort: \\Task.title) — type-safe and refactor-friendly.
• 💡 SwiftData often autosaves, so you rarely call save() yourself.
• 💡 Target iOS 17+; fall back to Core Data when you must support older systems.

Common Errors (and the fix)

• Objects never persist — you didn't attach a .modelContainer(for:) for the type.
• "@Model requires a class" — apply the macro to a final class , not a struct.
• List doesn't update — fetch with @Query , not a manual array.
• "Available in iOS 17 or newer" — SwiftData needs an iOS 17+ deployment target.

📋 Quick Reference

Task

Code

Result

Model

@Model final class Task

persistent

Storage

.modelContainer(for: Task.self)

sets up store

Fetch

@Query var tasks: [Task]

live results

Add

context.insert(task)

new object

Remove

context.delete(task)

removed

Frequently Asked Questions

Mini-Challenge: SwiftData To-Do

Build a small @Model-backed to-do list with @Query, insert, and delete — and notice how little code it takes.

🎉 Lesson Complete!

• ✅ @Model makes a Swift class persistent — no model file
• ✅ A ModelContainer sets up storage at the app root
• ✅ @Query fetches and observes models with type-safe sorting
• ✅ context.insert(_:) and context.delete(_:) add and remove
• ✅ SwiftData is the code-first, less-boilerplate successor to Core Data (iOS 17+)
• ✅ Next lesson: Unit Testing with XCTest

Practice quiz

Continue this course

• Previous: Persistence with Core Data
• Next: Unit Testing with XCTest