FactoryExample

SwiftFactory.swift

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

import Foundation

// All views implement this protocol.
protocol CustomView {
    func render() -> String
}

// When no parameters are supplied
// let's return this empty view.
class EmptyView: CustomView {
    func render() -> String {
        return ""
    }
}

// When > 0 parameters, let's return this view.
class FilledView: CustomView {
    var strings: [String]!
    
    // We instantiate with the parameters, because they aren't empty,
    // we can assume them able to be explicitly unwrapped.
    init(_ parameters: [String]) {
        self.strings = parameters
    }
    
    // Just simply spit out all strings with a new-line.
    func render() -> String {
        var finalString = ""
        strings.forEach { finalString.append("\($0)\n") }
        return finalString
    }
}

// Our factory with static ::make() method.
// It simply checks the parameters and then returns either
// a FilledView() or an EmptyView().
class ViewFactory {
    static func make(_ parameters: [String]) -> CustomView? {
        return parameters.count > 0 ? FilledView(parameters) : EmptyView()
    }
}

// parameters.count == 0, no filled view.
let parameters = [String]()
let emptyView = ViewFactory.make(parameters)
emptyView?.render() // returns an empty string.

// parameters.count > 0, a filled view.
let newParameters = ["This is a string", "This is another one"]
let filledView = ViewFactory.make(newParameters)
filledView?.render() // returns a string of all of the passed in strings.