You need to provide an implementation for the move method

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) {
        switch direction {
            case .up: location.y += 1
            case .down: location.y -= 1
            case .right: location.x += 1
            case .left: location.x -= 1
        }

        print(location.x, location.y)
    }
}

let player = Robot()
player.location = Point(x: 33, y: 2)
player.move(direction: .up)
player.move(direction: .down)