NEW: Nominations are now open for the 2019 Swift Community Awards! >>

How to use ISO-8601 dates with JSONDecoder and Codable

Swift version: 5.1

Paul Hudson    @twostraws   

Encoding and decoding dates using the Codable protocol isn’t hard to do, but it does produce some unexpected data by default: Date stores its information as a floating-point number counting the number of seconds since January 1st 2001, rather than something standard involved days, months, and years.

ISO-8601 is the web’s standard way of referring to dates and times, and looks like this: 2018-12-25T17:30:00Z – in English that’s December 25th 2018, at 5:30pm UTC. Both JSONEncoder and JSONDecoder are able to use this date format rather than the floating-point default – all you have to do is set their dateEncodingStrategy and dateDecodingStrategy properties.

If you’re decoding dates, use this:

let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601

And if you’re encoding dates you should use this:

let encoder = JSONEncoder()
encoder.dateEncodingStrategy = .iso8601

SAVE 20% ON iOS CONF SG The largest iOS conference in Southeast Asia is back in Singapore for the 5th time in January 2020, now with two days of workshops plus two days of talks on SwiftUI, Combine, GraphQL, and more! Save a massive 20% on your tickets by clicking on this link.

Available from iOS 8.0

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.

MASTER SWIFT NOW
Buy Testing Swift Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift 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: 4.7/5