sinoru/swift-json

Features

• Type-safe dynamic JSON representation with JSON.Value
• High-precision number handling with JSONNumber (backed by Int128)
• Full Codable support (Encodable / Decodable)
• JSONValueDecoder for decoding JSON.Value into any Decodable type
• Build JSON using Swift literal syntax (dictionaries, arrays, strings, numbers, booleans, nil)
• Sendable conformance for Swift 6 concurrency

Requirements

• Swift 6.0+
• macOS 15+ / iOS 18+ / tvOS 18+ / watchOS 11+ / visionOS 2+

Installation

Add the dependency to your Package.swift:

dependencies: [
    .package(url: "https://github.com/sinoru/swift-json.git", from: "0.2.0"),
]

Then add the modules you need to your target:

.target(
    name: "YourTarget",
    dependencies: [
        .product(name: "JSON", package: "swift-json"),
        .product(name: "JSONValueCoder", package: "swift-json"),
    ]
),

Usage

Building JSON with Literals

JSON.Value conforms to Swift's ExpressibleBy*Literal protocols, so you can construct JSON naturally:

import JSON

let value: JSON.Value = [
    "name": "Swift JSON",
    "version": 2,
    "tags": ["json", "swift", "codable"],
    "active": true,
    "metadata": nil,
]

Encoding and Decoding

JSON.Value works directly with Foundation's JSONEncoder and JSONDecoder:

import Foundation
import JSON

// Decode JSON data into JSON.Value
let data = Data(#"{"name":"Swift","year":2014}"#.utf8)
let value = try JSONDecoder().decode(JSON.Value.self, from: data)

// Encode JSON.Value back to JSON data
let encoded = try JSONEncoder().encode(value)

Accessing Values

Use subscripts and optional properties to navigate JSON structures:

let name = value["name"]?.string    // Optional("Swift")
let year = value["year"]?.number    // Optional(JSONNumber)

// With a default value
let missing = value["unknown", default: "fallback"]

// Array access
let tags: JSON.Value = ["a", "b", "c"]
let first = tags[0]?.string         // Optional("a")

Precise Number Handling

JSONNumber uses Int128 significand for ~38-digit decimal precision, avoiding floating-point artifacts:

import JSONNumber

let price = JSONNumber(significand: 1999, exponent: -2) // 19.99
let double = Double(price)                               // 19.99
let decimal = Decimal(price)                              // 19.99

Decoding JSON.Value into Swift Types

Use JSONValueDecoder to decode a JSON.Value into any Decodable type:

import JSON
import JSONValueCoder

struct User: Decodable {
    let name: String
    let age: Int
}

let json: JSON.Value = ["name": "Jaehong", "age": 30]
let user = try JSONValueDecoder().decode(User.self, from: json)

Modules

| Module | Description | |---|---| | JSON | Core types: JSON.Value, JSON.Object, JSON.Array, JSON.Number | | JSONValueCoder | JSONValueDecoder for decoding JSON.Value into Decodable types |

Documentation

Full API documentation is available on Swift Package Index.

License

This project is licensed under the Apache License 2.0. See LICENSE for details.

Package Metadata

Repository: sinoru/swift-json

Default branch: main

README: README.md