json_repair_ios

json_repair_ios is a small Swift package for repairing malformed JSON commonly produced by LLMs before decoding it on Apple platforms.

It is inspired by the MIT-licensed Python project mangiucugna/json_repair, with a native Swift implementation and no runtime dependencies.

What It Repairs

• Missing quotes around object keys and bare string values
• Single-quoted strings and curly quotes
• Trailing commas and missing commas between object members
• Truncated true, false, and null literals
• JavaScript/Python-style booleans and nulls (True, False, None)
• Line comments, block comments, and # comments
• Markdown fenced JSON blocks and JSONP wrappers
• Stray ellipsis entries in arrays
• Unclosed arrays, objects, and strings when a valid repair is possible

This package is intentionally heuristic. It is designed as a fallback for model output, not as a replacement for strict validation of trusted protocols.

Installation

Add the package with Swift Package Manager:

.package(url: "https://github.com/GP-Moon/json_repair_ios.git", branch: "main")

Then add the product:

.product(name: "JSONRepairIOS", package: "json_repair_ios")

Usage

import JSONRepairIOS

let badJSON = #"{"users":[{"name":"Ada","role":"admin",}],"ok":tru"#
let repaired = try JSONRepair.repair(badJSON)
// {"users":[{"name":"Ada","role":"admin"}],"ok":true}

Decode directly into a Decodable type:

struct Payload: Decodable {
    let name: String
    let enabled: Bool
}

let payload = try JSONRepair.decode(Payload.self, from: "{name: 'Pokebot', enabled: True}")

Inspect the repaired value without serializing:

let value = try JSONRepair.loads("{items: [1, 2, false]}")

API

• JSONRepair.repair(_:options:) -> String
• JSONRepair.loads(_:options:) -> JSONValue
• JSONRepair.decode(_:from:options:decoder:) -> Decodable

JSONRepairOptions supports:

• skipValidation: skip the strict JSONSerialization fast path and go straight to repair.
• prettyPrinted: emit formatted JSON.
• sortKeys: serialize object keys alphabetically.

Requirements

• Swift 5.9+
• iOS 17+
• macOS 14+

Development

swift build
swift test

License

MIT. See LICENSE.