Swift4のCodableでフラットなJSONからネストしたオブジェクトにデコードしてみた。値は取得できたけど、これで正しい方法なのかな？ #swift #CodePiece

CodePiece.swift

import Foundation

struct User: Codable {
    struct Address: Codable {
        let street: String
        let city: String
        let state: String
    }
    let name: String
    let address: Address
    
    private enum UserCodingKeys: String, CodingKey {
        case name
        case address
    }
    
    private enum AddressCodingKeys: CodingKey {
        case street
        case city
        case state
    }
    
    public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: UserCodingKeys.self)
        name = try container.decode(String.self, forKey: .name)
        
        let addressContainer = try decoder.container(keyedBy: AddressCodingKeys.self)
        let street = try addressContainer.decode(String.self, forKey: .street)
        let city = try addressContainer.decode(String.self, forKey: .city)
        let state = try addressContainer.decode(String.self, forKey: .state)
        address = Address(street: street, city: city, state: state)
    }
}

let data = """
{
"name": "rizumita",
"street": "1-2-3 Foo",
"city": "Bar",
"state": "Baz"
}
""".data(using: .utf8)!

let decoder: JSONDecoder = JSONDecoder()
do {
    let user: User = try decoder.decode(User.self, from: data)
    print(user)
} catch {
    print(error.localizedDescription)
}