Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

iOS Enumerations and Optionals in Swift Introduction to Enumerations Enums and Objects

Carlos Mendez
Carlos Mendez
2,646 Points

I am not sure how to increase or decrease the location stored property of the Robot class.

Hi there!

I am blanking out and not sure how to implement the method for Robot using the Enum. I am not really sure how I can add or subtract one to Point by applying each member of the enum.

I tried it with an if statement, which I figured wouldn't work.


class Point {
    var x: Int
    var y: Int

    init(x: Int, y: Int) {
        self.x = x
        self.y = y

enum Direction {
    case left
    case right
    case up
    case down

class Robot {
    var location: Point

    init() {
        self.location = Point(x: 0, y: 0)

     func move(_ direction: Direction) -> Point {
        switch direction {
        case Direction.down: return Point(x: 0, y: -1)
        case Direction.up: return Point(x: 0, y: 1)
        case Direction.right: return Point(x: 1, y: 0)
        case Direction.left: return Point(x: -1, y: 1)

1 Answer

Some hints:

1) The move function doesn't return anything. It just updates the current location.

2) location.x stores the current x coordinate for Robot. So

location.x = location.x + 1


location.x += 1

would move 1 step to the right.