Swift version: 5.10
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)
}
}
SPONSORED Transform your career with the iOS Lead Essentials. Unlock over 40 hours of expert training, mentorship, and community support to secure your place among the best devs. Click for early access to this limited offer and a FREE crash course.
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
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
Link copied to your pasteboard.