JSON model decoding based on yyjson.
Consider the following JSON:
{
"profile": {
"nickname": "NIX",
"username": "@nixzhu@mastodon.social",
"avatar": {
"url": "https://example.com/nixzhu.png",
"width": 200,
"height": 200
}
},
"toots": [
{
"id": 1,
"content": "Hello World!",
"created_at": "2024-10-05T09:41:00.789Z"
},
{
"id": 2,
"content": "How do you do?",
"created_at": "2025-04-29T22:23:24.567Z"
}
]
}We can create models conforming to the AnandaModel protocol as follows:
import Foundation
import Ananda
struct Mastodon: AnandaModel {
let profile: Profile
let toots: [Toot]
init(json: AnandaJSON) {
profile = .decode(from: json.profile)
toots = json.toots.array().map { .decode(from: $0) }
}
}
extension Mastodon {
struct Profile: AnandaModel {
let nickname: String
let username: String
let avatar: Avatar
init(json: AnandaJSON) {
nickname = json.nickname.string()
username = json.username.string()
avatar = .decode(from: json.avatar)
}
}
}
extension Mastodon.Profile {
struct Avatar: AnandaModel {
let url: URL
let width: Double
let height: Double
init(json: AnandaJSON) {
url = json["url"].url()
width = json.width.double()
height = json.height.double()
}
}
}
extension Mastodon {
struct Toot: AnandaModel {
let id: Int
let content: String
let createdAt: Date
init(json: AnandaJSON) {
id = json.id.int()
content = json.content.string()
createdAt = json.created_at.date()
}
}
}To decode a Mastodon instance from a JSON string:
let mastodon = Mastodon.decode(from: jsonString)Or, if you already have JSON data:
let mastodon = Mastodon.decode(from: jsonData)To decode a specific JSON branch, for example profile.avatar, specify its path:
let avatar = Mastodon.Profile.Avatar.decode(from: jsonData, path: ["profile", "avatar"])To decode an array (e.g., toots):
let toots = [Mastodon.Toot].decode(from: jsonData, path: ["toots"])Or decode only the first toot:
let toot = Mastodon.Toot.decode(from: jsonData, path: ["toots", 0])With AnandaMacros, you can use macros to eliminate the need for initialization methods, as shown below:
import Foundation
import Ananda
import AnandaMacros
@AnandaInit
struct Mastodon: AnandaModel {
let profile: Profile
let toots: [Toot]
}
extension Mastodon {
@AnandaInit
struct Profile: AnandaModel {
let nickname: String
let username: String
let avatar: Avatar
}
}
extension Mastodon.Profile {
@AnandaInit
struct Avatar: AnandaModel {
let url: URL
let width: Double
let height: Double
}
}
extension Mastodon {
@AnandaInit
struct Toot: AnandaModel {
let id: Int
let content: String
@AnandaKey("created_at")
let createdAt: Date
}
}Simple and clean, right?
See AnandaBenchmark.
You can use Ducky Model Editor to generate AnandaModel from JSON, saving you time.