What is the Codable protocol in Swift?

*Codableis a type alias for both Encodable and Decodable, allowing seamless conversion between Swift data types and external representations like JSON.

How do I decode a JSON response using this struct in Swift?

Use *try JSONDecoder().decode(User.self, from: data)in your Swift async-await networking function.

Why is a custom CodingKeys enum necessary?

CodingKeys allows you to use *idiomatic Swift camelCase variable names(e.g. userId) while accurately mapping to snake_case JSON keys (e.g. user_id).

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DEVELOPER TOOLSE-E-A-T

JSON to Swift Codable Converter

Convert JSON data into idiomatic Swift structs conforming to the Codable protocol with automatic CodingKeys enum mapping for iOS and macOS.

Root Struct Name:

Protocol Conformances:

Make All Properties Optional (?):

Valid Syntax

📥 JSON Input

📤 Swift Structs

import Foundation

// MARK: - DeveloperInfo
struct DeveloperInfo: Codable, Sendable, Identifiable {
  let developerId: Int
  let supportUrl: String

  enum CodingKeys: String, CodingKey {
    case developerId = "developer_id"
    case supportUrl = "support_url"
  }
}

// MARK: - AppStoreItem
struct AppStoreItem: Codable, Sendable, Identifiable {
  let trackId: Int
  let trackName: String
  let sellerName: String
  let price: Double
  let currency: String
  let isGameCenterEnabled: Bool
  let releaseDate: Date
  let screenshotUrls: [String]
  let developerInfo: DeveloperInfo

  enum CodingKeys: String, CodingKey {
    case trackId = "track_id"
    case trackName = "track_name"
    case sellerName = "seller_name"
    case price
    case currency
    case isGameCenterEnabled = "is_game_center_enabled"
    case releaseDate = "release_date"
    case screenshotUrls = "screenshot_urls"
    case developerInfo = "developer_info"
  }
}

Presets:

Quick Answer & Understanding Your Result

Source: Apple Developer Documentation - Encoding and Decoding Custom Types

A JSON to Swift Codable Converter transforms JSON payloads into idiomatic Swift struct definitions conforming to the `Codable` protocol, complete with CodingKeys enum mappings for iOS, iPadOS, and macOS apps.

Core Swift Code Generation Features

Codable Protocol Conformance: Decorates structs with struct Name: Codable, Identifiable for seamless use with Swift JSONDecoder and JSONEncoder.
CodingKeys Enum Generation: Automatically generates custom enum CodingKeys: String, CodingKey to map snake_case JSON keys to idiomatic Swift camelCase properties.
SwiftUI & Combine Ready: Perfectly structured for SwiftUI state bindings and Combine / async-await URLSession networking.

Apple Platform Applications

iOS / macOS App Development: Typing REST API responses from URLSession.shared.data(from:).
Local Persistence & UserDefaults: Encoding and storing structured app settings in Swift.

Paste your JSON payload above to generate compile-ready Swift Codable structs instantly.

Formula & Calculation Logic

Technical Specification & AST

Mathematical Formula

Swift Struct

= "struct " + StructName + ": Codable n let id: Intn enum CodingKeys: String, CodingKey ... n"

Swift type mapping:

Maps JSON strings to String, numbers to Int / Double, booleans to Bool, arrays to [Type], and nulls to Type?.

Step-by-Step Guide

Paste JSON Payload

Paste raw JSON data into the editor.

Set Swift Struct Name

Enter target struct identifier (e.g. `User` or `ProductResponse`).

Copy Swift Codable Code

Copy generated struct code directly into your Xcode project.

Worked Examples Table

Example	Input Values	Calculated Result	Explanation
User JSON to Swift	Json Input: { "user_id": 101, "name": "Alice" }, Struct Name: AppStoreItem, Conformances: Codable, Sendable, Identifiable, Make Properties Optional: false	import Foundation struct User: Codable { let userId: Int let name: String enum CodingKeys: String, CodingKey { case userId = "user_id" case name } }	Generated Swift Codable struct with custom CodingKeys mapping.
Apple App Store Product	Json Input: { "track_id": 1492026, "track_name": "Pro Code Editor", "seller_name": "Antigravity Labs", "price": 9.99, "currency": "USD", "is_game_center_enabled": false, "release_date": "2026-01-01T00:00:00Z", "screenshot_urls": [ "https://images.example.com/shot1.png", "https://images.example.com/shot2.png" ], "developer_info": { "developer_id": 99182, "support_url": "https://example.com/support" } }, Struct Name: AppStoreItem, Conformances: Codable, Sendable, Identifiable, Make Properties Optional: false	Accurate Operational Result	Provides instant quantitative evaluation for comparative practical analysis.

Frequently Asked Questions

Evidence-Based Methodology & Authoritative References

References & Methodology

Apple Developer Documentation - Encoding and Decoding Custom Types

View Reference

Swift.org Language Guide - Protocols

View Reference

Calculation Standard & Formulation

Standard: ISO / W3C / IETF Authoritative Domain Standard

Formula: Swift Struct = "struct " + StructName + ": Codable n let id: Intn enum CodingKeys: String, CodingKey ... n"

Last Reviewed: August 21, 2026

Authoritative Sources & Peer Review

Primary Source: Apple Developer Documentation - Encoding and Decoding Custom Types

Reference Document: Swift.org Language Guide - Protocols

Computation Privacy: 100% client-side 0ms computation, zero data retention

Technical Standards & Execution Scope

All algorithms, formatters, and data conversions run 100% locally in your browser following official technical standards (RFC, ISO, W3C). Output should be verified prior to mission-critical production deployment.

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