ORM for Swift (iOS/macOS): comparison and usage examples

ORM for Swift (iOS/macOS): comparison and examples

When developing applications for iOS and macOS, developers often face the need to store data on the device. To simplify working with databases, ORM (Object-Relational Mapping) libraries are used — libraries that allow you to work with data as regular Swift objects, hiding the complexity of SQL queries. In this article, we will look at four popular solutions: Core Data, Realm, GRDB, and SQLite.swift, compare their capabilities, and provide practical examples.

1. Core Data

Core Data is a framework from Apple, built into iOS and macOS. It is not a pure ORM, but rather a framework for managing an object graph that can use SQLite, XML, or binary storage.

Advantages:

• Deep integration with the Apple ecosystem (SwiftUI, iCloud, Undo Manager).
• Visual data model editor (Xcode Data Modeler).
• Support for versioning and migrations.

Disadvantages:

• High entry barrier (a lot of boilerplate code).
• Performance issues when working with large datasets.
• Tight binding to Apple platforms.

Code example (Swift):

import CoreData

// Creating a contextlet container = NSPersistentContainer(name: "Model")container.loadPersistentStores { _, error in    if let error = error { print(error) }}

// Saving an objectlet context = container.viewContextlet user = User(context: context)user.name = "Ivan"user.age = 30

try? context.save()

// Querylet request: NSFetchRequest<User> = User.fetchRequest()request.predicate = NSPredicate(format: "age > 18")let users = try? context.fetch(request)

2. Realm

Realm is a cross-platform ORM designed specifically for mobile applications. It is faster than Core Data on read and write operations.

Advantages:

• High performance (up to 10x faster than Core Data).
• Simple API without needing to write SQL.
• Automatic object updates (live objects).
• Support for reactive extensions (RxRealm, Combine).

Disadvantages:

• Proprietary database file format.
• Limited database size (up to 2 GB on iOS).
• Less flexibility for complex queries.

Code example (Swift):

import RealmSwift

// Model definitionclass User: Object {    @Persisted var name: String = ""    @Persisted var age: Int = 0}

// Savinglet realm = try! Realm()let user = User()user.name = "Maria"user.age = 25

try! realm.write {    realm.add(user)}

// Querylet users = realm.objects(User.self).filter("age > 18")for user in users {    print("\\(user.name): \\(user.age)")}

3. GRDB

GRDB is a modern library for working with SQLite in Swift. It combines the capabilities of low-level SQL access with the convenience of ORM.

Advantages:

• Maximum performance (native SQLite).
• Support for Combine and Swift Concurrency (async/await).
• Full control over SQL queries.
• Support for migrations and versioning.

Disadvantages:

• Requires knowledge of SQL.
• Less "magic" — more manual code.

Code example (Swift):

import GRDB

// Model definitionstruct User: Codable, FetchableRecord, PersistableRecord {    var id: Int64?    var name: String    var age: Int}

// Connecting to the databaselet dbQueue = try DatabaseQueue(path: "/path/to/database.sqlite")

// Savingtry dbQueue.write { db in    let user = User(nam