Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

iOS Protocols in Swift Protocol Basics Protocols With Methods

Adam Petritsis
Adam Petritsis
2,942 Points

Which is the right way to change the lamp color?

For this task, make WifiLamp adopt the ColorSwitchable protocol. In the implementation of the method, simply set the color of the lamp to the new color.

// Declare protocol here
protocol ColorSwitchable {
func switchColor(_ color: Color) -> Color 

enum LightState {
  case on, off

enum Color {
  case rgb(Double, Double, Double, Double)
  case hsb(Double, Double, Double, Double)

class WifiLamp: ColorSwitchable {
  let state: LightState
  var color: Color

  init() {
    self.state = .on
    self.color = .rgb(0,0,0,0)

  func switchColor(_ color: Color) -> Color {



1 Answer

Adam Petritsis,

There is a little problem in the protocol declaration and that is that the switchColor function doesn't return a Color. Also, in the implementation of the switchColor, you will have to assign the color from the argument to the instance member color. For example:

func switchColor(_ color: Color) {
    self.color = color

Fix the protocol declaration and let me know if you have any other questions.


Adam Petritsis
Adam Petritsis
2,942 Points

Thank you Daniel that worked. It had passed the first step of the exercise with the function returning Color, so i thought that was correct.

Great! That is probably because Pasan Premaratne is not testing for it in that particular step.