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

Arius Eich
Arius Eich
2,769 Points

Altering an integer in a function

How do I alter the values in the point struct and then have it return that correctly? Thank you!

test.swift
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)
    }

class Robot {
    var location: Point

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

    func move(_ direction: Direction) -> Point {
        // Enter your code below
        switch direction {
        case Direction.left  : return Point(x: x - 1, y: y)
        case Direction.right : return Point(x: x + 1, y: y)
        case Direction.up    : return Point(x: x, y: y + 1)
        case Direction.down  : return Point(x: x, y: y - 1)

        }
    }
}

2 Answers

Everton Carneiro
Everton Carneiro
15,994 Points

Hello mate. I was not sure what you are asking but I found some mistakes in your code. First, for some reason (or by mistake) you copy your Robot class inside of itself.

Second, in this function you wrote:

    func move(_ direction: Direction) -> Point {
        // Enter your code below
        switch direction {
        case Direction.left  : return Point(x: x - 1, y: y)
        case Direction.right : return Point(x: x + 1, y: y)
        case Direction.up    : return Point(x: x, y: y + 1)
        case Direction.down  : return Point(x: x, y: y - 1)

        }
    }

Where you say: return Point(x: x - 1, y: y) you are passing a 'x' as an argument that doesn't exist. I know what you are trying to do, but you can't do like that.

Your third mistake was try to use Point to change the location of the Robot. You are supposed to use location to change the x and y of the robot since location is an instance of Point. You just need to update the x or y in the location instance, like this:

class Robot {
    var location: Point

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

    func move(_ direction: Direction) {
        // Enter your code below
        switch direction {
        case Direction.left:
            return location.x -= 1
        case Direction.right:
            return location.x += 1
        case Direction.up:
            return location.y += 1
        case Direction.down :
            return location.y -= 1

        }
    }
}

I hope this helps.

Arius Eich
Arius Eich
2,769 Points

Thank you! I appreciate it.