NEW: My new book Pro SwiftUI is out now – level up your SwiftUI skills today! >>

How to load and save a struct in UserDefaults using Codable

Swift version: 5.6

Paul Hudson    @twostraws   

The Codable protocol makes it easy to load and save native Swift types to JSON, and with a little typecasting you can get that data into UserDefaults so it’s safe.

Here’s some trivial Codable data we can work with:

struct Person: Codable {
    var name: String
}

let taylor = Person(name: "Taylor Swift")

To save that to UserDefaults you must first encode it as JSON using JSONEncoder, which will send back a Data instance you can send straight to UserDefaults. For example:

let encoder = JSONEncoder()
if let encoded = try? encoder.encode(taylor) {
    let defaults = UserDefaults.standard
    defaults.set(encoded, forKey: "SavedPerson")
}

Reading saved data back into a Person instance is a matter of converting from Data using a JSONDecoder, like this:

if let savedPerson = defaults.object(forKey: "SavedPerson") as? Data {
    let decoder = JSONDecoder()
    if let loadedPerson = try? decoder.decode(Person.self, from: savedPerson) {
        print(loadedPerson.name)
    }
}
Hacking with Swift is sponsored by Play

SPONSORED Play is the first native iOS design tool created for designers and engineers. You can install Play for iOS and iPad today and sign up to check out the Beta of our macOS app with SwiftUI code export. We're also hiring engineers!

Click to learn more about Play!

Sponsor Hacking with Swift and reach the world's largest Swift community!

Available from iOS 8.0 – learn more in my book Swift Design Patterns

Similar solutions…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

BUY OUR BOOKS
Buy Pro Swift Buy Pro SwiftUI Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.4/5

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.