archiver.swift

//
//  archiver.swift
//
//  Created by JK on 2020/02/27.
//  Copyright © 2020 codesquad. All rights reserved.
//

import Foundation

class NBeverage : NSObject, NSCoding, Codable {
    private var brand : String = ""
    private enum CodingKeys: String, CodingKey {
        case brand
    }
    
    init(brand : String) {
        self.brand = brand
    }
    
    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.brand = try container.decode(String.self, forKey: .brand)
    }
    
    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(brand, forKey: .brand)
    }
    
    required init?(coder: NSCoder) {
        self.brand = coder.decodeObject(forKey: "brand") as! String
    }
    
    func encode(with coder: NSCoder) {
        coder.encode(brand, forKey: "brand")
    }
    
    override var description: String {
        return "Beverage(\(brand))"
    }
}

class NCoffee : NBeverage {
    private var caffeine : Double = 0
    private enum CodingKeys: String, CodingKey {
        case caffeine
    }
    
    init(brand : String, caffeine : Double) {
        self.caffeine = caffeine
        super.init(brand: brand)
    }

    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.caffeine = try container.decode(Double.self, forKey: .caffeine)
        try super.init(from: decoder)
    }
    
    override func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(caffeine, forKey: .caffeine)
        try super.encode(to: encoder)
    }
    
    required init?(coder: NSCoder) {
        self.caffeine = coder.decodeDouble(forKey: "caffeine")
        super.init(coder: coder)
    }
    
    override func encode(with coder: NSCoder) {
        coder.encode(caffeine, forKey: "caffeine")
        super.encode(with: coder)
    }
    
    override var description: String {
        return "Coffee(\(caffeine))-(\(super.description))"
    }
}

class NSoda : NBeverage {
    private var nitrogen : Double = 0
    private enum CodingKeys: String, CodingKey {
        case nitrogen
    }
    
    init(brand: String, nitrogen : Double) {
        self.nitrogen = nitrogen
        super.init(brand: brand)
    }
    
    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.nitrogen = try container.decode(Double.self, forKey: .nitrogen)
        try super.init(from: decoder)
    }
    
    override func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(nitrogen, forKey: .nitrogen)
        try super.encode(to: encoder)
    }
    
    required init?(coder: NSCoder) {
        self.nitrogen = coder.decodeDouble(forKey: "nitrogen")
        super.init(coder: coder)
    }
    
    override func encode(with coder: NSCoder) {
        coder.encode(nitrogen, forKey: "nitrogen")
        super.encode(with: coder)
    }
    
    override var description: String {
        return "Soda(\(nitrogen))-(\(super.description))"
    }
}

class NCoke : NSoda {
    private var diet : Bool = false
    private enum CodingKeys: String, CodingKey {
        case diet
    }
    
    init(brand: String, nitrogen: Double, diet: Bool) {
        self.diet = diet
        super.init(brand: brand, nitrogen: nitrogen)
    }
    
    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.diet = try container.decode(Bool.self, forKey: .diet)
        try super.init(from: decoder)
    }
    
    override func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(diet, forKey: .diet)
        try super.encode(to: encoder)
    }
    
    required init?(coder: NSCoder) {
        self.diet = coder.decodeBool(forKey: "diet")
        super.init(coder: coder)
    }
    
    override func encode(with coder: NSCoder) {
        coder.encode(diet, forKey: "diet")
        super.encode(with: coder)
    }
    
    override var description: String {
        return "Coke(\(diet))-(\(super.description))"
    }
}


func archive(with things: [NBeverage]) -> Data {
    do {
        let archived = try NSKeyedArchiver.archivedData(withRootObject: things, requiringSecureCoding: false)
        return archived
    }
    catch {
        print(error)
    }
    return Data()
}

func unarchive(with text: Data) -> [NBeverage]? {
    do {
        let object = try NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(text)
        return object as? [NBeverage]
    }
    catch {
        print(error)
    }
    return []
}

codable.swift

//
//  codable.swift
//
//  Created by JK on 2020/02/27.
//  Copyright © 2020 codesquad. All rights reserved.
//

import Foundation

class Beverage : Codable, CustomStringConvertible {
    private var brand : String = ""
    private enum CodingKeys: String, CodingKey {
        case brand
    }
    
    init(brand : String) {
        self.brand = brand
    }
    
    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.brand = try container.decode(String.self, forKey: .brand)
    }
    
    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(brand, forKey: .brand)
    }
    
    var description: String {
        return "Beverage(\(brand))"
    }
}

class Coffee : Beverage {
    private var caffeine : Double = 0
    private enum CodingKeys: String, CodingKey {
        case caffeine
    }
    
    init(brand : String, caffeine : Double) {
        self.caffeine = caffeine
        super.init(brand: brand)
    }

    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.caffeine = try container.decode(Double.self, forKey: .caffeine)
        try super.init(from: decoder)
    }
    
    override func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(caffeine, forKey: .caffeine)
        try super.encode(to: encoder)
    }
        
    override var description: String {
        return "Coffee(\(caffeine))-(\(super.description))"
    }
}

class Soda : Beverage {
    private var nitrogen : Double = 0
    private enum CodingKeys: String, CodingKey {
        case nitrogen
    }
    
    init(brand: String, nitrogen : Double) {
        self.nitrogen = nitrogen
        super.init(brand: brand)
    }
    
    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.nitrogen = try container.decode(Double.self, forKey: .nitrogen)
        try super.init(from: decoder)
    }
    
    override func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(nitrogen, forKey: .nitrogen)
        try super.encode(to: encoder)
    }
    
    override var description: String {
        return "Soda(\(nitrogen))-(\(super.description))"
    }
}

class Coke : Soda {
    private var diet : Bool = false
    private enum CodingKeys: String, CodingKey {
        case diet
    }
    
    init(brand: String, nitrogen: Double, diet: Bool) {
        self.diet = diet
        super.init(brand: brand, nitrogen: nitrogen)
    }
    
    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.diet = try container.decode(Bool.self, forKey: .diet)
        try super.init(from: decoder)
    }
    
    override func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(diet, forKey: .diet)
        try super.encode(to: encoder)
    }
        
    override var description: String {
        return "Coke(\(diet))-(\(super.description))"
    }
}

func encode(with things: [Beverage]) -> String {
    let jsonEncoder = JSONEncoder()
    do {
        let json = try jsonEncoder.encode(things)
        return String(data: json, encoding: .utf8) ?? ""
    }
    catch {
        print(error)
    }
    return ""
}

func decode(with text: String) -> [Beverage] {
    let jsonDecoder = JSONDecoder()
    do {
        let jsonObject = try jsonDecoder.decode([Beverage].self, from: text.data(using: .utf8) ?? Data())
        return jsonObject
    }
    catch {
        print(error)
    }
    return []
}

example-archiver.swift

let ndrinks : [NBeverage] = [ NCoke(brand: "Coca", nitrogen: 50, diet: true),
                              NCoffee(brand: "TOP", caffeine: 256),
                              NCoke(brand: "Pepsi", nitrogen: 51, diet: false) ]

let archiveText = archive(with: ndrinks)
let archiveObject = unarchive(with: archiveText)
result = ""
archiveObject?.forEach{
    result += $0.description + ", "
}
print(result)

example-codable.swift

let drinks : [Beverage] = [ Coke(brand: "Coca", nitrogen: 50, diet: true),
                            Coffee(brand: "TOP", caffeine: 256),
                            Coke(brand: "Pepsi", nitrogen: 51, diet: false) ]

let jsonText = encode(with: drinks)
let jsonObject = decode(with: jsonText)
var result = ""
jsonObject.forEach{
  result += $0.description + ", "
}
print(result)

/*
 Swift 4 Decodable Loses Subclass Type Information
 https://bugs.swift.org/browse/SR-5331

 This is by design — if you need the dynamism required to do this, we recommend that you adopt NSSecureCoding and use NSKeyedArchiver/NSKeyedUnarchiver, which will allow you to decode based on the class found in the archive rather than what is requested at runtime. See https://developer.apple.com/documentation/foundation/nscoding and https://developer.apple.com/documentation/foundation/nssecurecoding for more info.
*/