设计模式之 Factory Mode 工厂模式：Swift 实现_swift在父类中创建子类对象的工厂方法-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_39147809/article/details/125919209

本文介绍了工厂模式在Swift编程中的实现，通过定义蛋糕创建者协议和产品协议，实现了不同类型的蛋糕（如MongoCake和ChocolateCake）的创建。工厂方法将核心业务逻辑与具体产品类分离，使得代码更具扩展性。若要新增蛋糕类型，只需遵循协议并创建相应创建者即可。

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Factory Mode 工厂模式

Provide the method for creating an instance in the superclass, and allow the subclass to choose the type of the instance.

在父类中提供创建对象的方法，允许子类决定实例化对象的类型。

具备的部分：生产者协议、产品协议，往后就可以根据需要来扩展每一种产品。

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具体的生产者比如 MongoCakeCreator 的存在是为了实现与产品相关的核心业务逻辑，而不仅仅是创建 MongoCake 实例。工厂方法将核心业务逻辑从具体产品类中分离出来。

// Creator
protocol CakeCreator {
    func createCake() -> Cake
    func doSomethingForCake(cake: Cake) -> Cake
}

// Product
protocol Cake {
    func doWork()
}

// ConcreteCreator
class MongoCakeCreator: CakeCreator {
    var cake: MongoCake?
    func createCake() -> Cake {
        var cake = MongoCake()
        doSomethingForCake(cake: cake)
        return cake
    }
    func doSomethingForCake(cake: Cake) -> Cake{
        cake.doWork()
        cake.doWork()
        return cake
    }
    
}

// ConcreteCreator
class ChocolateCakeCreator: CakeCreator {
    func createCake() -> Cake {
        var cake = ChocolateCake()
        doSomethingForCake(cake: cake)
        return cake
    }
    
    func doSomethingForCake(cake: Cake) -> Cake{
        cake.doWork()
        return cake
    }
}

class MongoCake: Cake {
    func doWork() {
        print("Add some mongo")
    }
}

class ChocolateCake: Cake {
    func doWork() {
        print("Add some chocolate")
    }
}

// If we want to add a type of cake call "PinapleCake", just need to 
// make it conform to Cake and add a creator that conform to the CakeCreator for the "PinapleCake"

let cakeOne = MongoCakeCreator().createCake()