Swift Codable init

Either you get everything for free but standardized or you have to write a custom initializer like

struct MyStruct: Codable  {    let id: Int     var name: String    private enum CodingKeys : String, CodingKey { case id, name }    init(from decoder: Decoder) throws {        let container = try decoder.container(keyedBy: CodingKeys.self)        id = try container.decode(Int.self, forKey: .id)        let decodedName = try container.decode(String.self, forKey: .name)        name = "\(id) \(decodedName)"     }}

You can implement init() but this works independent of the decoding functionality and you have to assign a default value to all non-optional properties, that's what the error says.

Use a factory method that first uses init(from:) and then calls your custom initialization code

struct Foo: Decodable {    let name: String    let id: Int    var x: String!    private mutating func finalizeInit() {        self.x = "\(name) \(id)"    }    static func createFromJSON(_ data: Data) -> Foo? {        guard var f = try? JSONDecoder().decode(Foo.self, from: data) else {             return nil         }        f.finalizeInit()        return f    }}let sampleData = """    { "name": "foo", "id": 42 }    """.data(using: .utf8)!let f = Foo.createFromJSON(sampleData)