JSON to Swift Codable Converter

From a JSON sample to a Swift struct

The output is a struct conforming to Codable with let properties, which is the default shape for a decoded API response. JSONDecoder matches property names to keys by name, so a payload that is already camelCase decodes with no further work.

Where you will need to intervene

• Snake_case keys. Either set keyDecodingStrategy to .convertFromSnakeCase on the decoder, or add a CodingKeys enum mapping each property to its raw key. The strategy is usually the smaller change, since the names here are already camelCased.
• Optional keys. Swift decoding is strict: a key missing from the response throws keyNotFound rather than leaving the property empty. Any field the server may omit has to be declared with ?.
• A JSON null in the sample yields Any?, which is not Codable and will not compile inside a Decodable type. Replace it with the concrete optional the field really holds.
• Arrays are typed from the first element. A heterogeneous array needs a custom init(from:) or an enum with associated values.
• Integer and floating point are read off the sample value, so Int will throw on a response that arrives with a decimal point.

For the Android half of the same API, JSON to Kotlin produces the equivalent data class, and JSON to Dart covers a Flutter client.