스위프트로 작성된 팩토리 메서드

import XCTest /// The Creator protocol declares the factory method that's supposed to return a /// new object of a Product class. The Creator's subclasses usually provide the /// implementation of this method. protocol Creator { /// Note that the Creator may also provide some default implementation of /// the factory method. func factoryMethod() -> Product /// Also note that, despite its name, the Creator's primary responsibility /// is not creating products. Usually, it contains some core business logic /// that relies on Product objects, returned by the factory method. /// Subclasses can indirectly change that business logic by overriding the /// factory method and returning a different type of product from it. func someOperation() -> String } /// This extension implements the default behavior of the Creator. This behavior /// can be overridden in subclasses. extension Creator { func someOperation() -> String { // Call the factory method to create a Product object. let product = factoryMethod() // Now, use the product. return "Creator: The same creator's code has just worked with " + product.operation() } } /// Concrete Creators override the factory method in order to change the /// resulting product's type. class ConcreteCreator1: Creator { /// Note that the signature of the method still uses the abstract product /// type, even though the concrete product is actually returned from the /// method. This way the Creator can stay independent of concrete product /// classes. public func factoryMethod() -> Product { return ConcreteProduct1() } } class ConcreteCreator2: Creator { public func factoryMethod() -> Product { return ConcreteProduct2() } } /// The Product protocol declares the operations that all concrete products must /// implement. protocol Product { func operation() -> String } /// Concrete Products provide various implementations of the Product protocol. class ConcreteProduct1: Product { func operation() -> String { return "{Result of the ConcreteProduct1}" } } class ConcreteProduct2: Product { func operation() -> String { return "{Result of the ConcreteProduct2}" } } /// The client code works with an instance of a concrete creator, albeit through /// its base protocol. As long as the client keeps working with the creator via /// the base protocol, you can pass it any creator's subclass. class Client { // ... static func someClientCode(creator: Creator) { print("Client: I'm not aware of the creator's class, but it still works.\n" + creator.someOperation()) } // ... } /// Let's see how it all works together. class FactoryMethodConceptual: XCTestCase { func testFactoryMethodConceptual() { /// The Application picks a creator's type depending on the /// configuration or environment. print("App: Launched with the ConcreteCreator1.") Client.someClientCode(creator: ConcreteCreator1()) print("\nApp: Launched with the ConcreteCreator2.") Client.someClientCode(creator: ConcreteCreator2()) } } 

App: Launched with the ConcreteCreator1. Client: I'm not aware of the creator's class, but it still works. Creator: The same creator's code has just worked with {Result of the ConcreteProduct1} App: Launched with the ConcreteCreator2. Client: I'm not aware of the creator's class, but it still works. Creator: The same creator's code has just worked with {Result of the ConcreteProduct2}