Strategy Pattern in Swift

strategyPattern.swift

import UIKit

/*
 What:
    A protocol that defines the action we want to encapsulate.
 
 Who:
    An object who contains an object who conforms the strategy.
 
 How:
    Specific implementation of the strategy. Each implementation is different.
 */


// What
protocol LoggerStrategy {
  func log(_ message: String)
}

// Who
struct Logger {
  let strategy: LoggerStrategy
  
  func log(_ message: String){
    strategy.log(message)
  }
}

// How
struct LowerCaseStrategy: LoggerStrategy {
  func log(_ message: String) {
    print(message.lowercased())
  }
}

struct UpperCaseStrategy: LoggerStrategy {
  func log(_ message: String) {
    print(message.uppercased())
  }
}


let lg1 = Logger(strategy: LowerCaseStrategy())
lg1.log("HELLO strategy")

let lg2 = Logger(strategy: UpperCaseStrategy())
lg2.log("Hello another strategy")