ProgrammerDIP.swift

protocol Coffee {
  func drink()
}

struct Americano: Coffee {
  func drink() {
    print("아메리카노를 마십니다.")
  }
}

struct Programmer {
  private let coffee: Coffee
	
  init(coffee: Coffee) {
    self.coffee = coffee
  }
	
  func startProgramming() {
    self.coffee.drink()
    //...
  }
}

let americano = Americano()
let programmer = Programmer(coffee: americano)
programmer.startProgramming()