How to Write a REST API in Swift in 30 Minutes

Introduction: Why Swift for REST API?

Swift is not only a language for mobile applications. Thanks to frameworks like Vapor and Kitura, you can create full-featured REST APIs for the server side. This is especially useful if your iOS app already uses Swift: you can write both the client and server in the same language, reducing development time and simplifying code maintenance.

In this article, we will create a simple REST API in Swift using the Vapor framework — the most popular solution for server-side development in Swift. We will set up the server, add routes for CRUD operations, and test it. The entire process will take no more than 30 minutes.

Requirements: macOS or Linux, installed Swift 5.8+ (or newer), basic understanding of HTTP and JSON.

Step 1: Installing and Setting Up a Vapor Project

Vapor provides a convenient CLI tool for a quick start. Install it via Homebrew:

brew install vapor

Then create a new project:

vapor new MyAPI --template=apicd MyAPI

The --template=api flag creates a scaffold with a minimal structure for a REST API. After creating the project, open it in Xcode (or any editor):

open Package.swift

The project structure includes:

• Sources/App/ — main logic (routes, controllers, models).
• Sources/App/routes.swift — route registration.
• Sources/App/configure.swift — application configuration.
• Package.swift — dependencies (Vapor is already included).

If you are using Xcode, it will automatically download dependencies. In the terminal, run vapor build to build.

Step 2: Creating the Data Model and Database

For a REST API, we need a model. Let's create a simple Task model with fields: id, title, completed. In Vapor, models usually inherit from Model (Fluent ORM).

Create a file Sources/App/Models/Task.swift:

import Fluentimport Vapor

final class Task: Model, Content {    static let schema = "tasks"

    @ID(key: .id)    var id: UUID?

    @Field(key: "title")    var title: String

    @Field(key: "completed")    var completed: Bool

    init() {}

    init(id: UUID? = nil, title: String, completed: Bool = false) {        self.id = id        self.title = title        self.completed = completed    }}

Now let's create a migration for the database table. Create a file Sources/App/Migrations/CreateTask.swift:

import Fluent

struct CreateTask: Migration {    func prepare(on database: Database) -> EventLoopFuture<Void> {        database.schema("tasks")            .id()            .field("title", .string, .required)            .field("completed", .bool, .required)            .create()    }

    func revert(on database: Database) -> EventLoopFuture<Void> {        database.schema("tasks").delete()    }}

Add the migration to configure.swift:

app.migrations.add(CreateTask())

By default, Vapor uses SQLite (a file in the project folder). If you want PostgreSQL or MySQL, change the settings in configure.swift, but for a quick start, SQLite works perfectly.

Step 3: Registering REST API Routes

Now let's create a controller to handle requests. Create a file Sources/App/Controllers/TaskController.swift:

import Vaporimport Fluent

struct TaskController: RouteCollection {    func boot(routes: RoutesBuilder) throws {        let tasks = routes.grouped("tasks")

        tasks.get(use: index)        // GET /tasks        tasks.post(use: create)      // POST /tasks        tasks.grou