Decoding values from silly heterogenous JSON arrays.

heterogenous.swift

//: Playground - noun: a place where people can play

import Foundation

let json = """
[
  {"person":{"name":"foo", "age":20}},
  {"house":{"size":"large"}}
]
""".data(using: .utf8)!

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

struct House: Decodable {
    let size: String
}

struct Heterogenous: Decodable {
    let person: Person
    let house: House

    enum ItemKeys: String, CodingKey {
        case person
        case house
    }
    
    init(from decoder: Decoder) throws {
        var values = try decoder.unkeyedContainer()
        person = try values.nestedContainer(keyedBy: ItemKeys.self).decode(Person.self, forKey: .person)
        house = try values.nestedContainer(keyedBy: ItemKeys.self).decode(House.self, forKey: .house)
    }
}

let decoder = JSONDecoder()
do {
    let things = try decoder.decode(Heterogenous.self, from: json)
    dump(things)
} catch {
    dump(error)
}