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iOS Build a Simple iPhone App with Swift 2.0 Getting Started with iOS Development Swift Recap Part 2

Ling Cheng
Ling Cheng
3,168 Points

Can't this be work too?

What's the problem with this one? Thanks!

class Point {
    var x: Int
    var y: Int

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

class Machine {
    var location: Point

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

    func move(direction: String) {
        print("Do nothing! I'm a machine!")

// Enter your code below
class Robot: Machine {

    override func move(direction: String) {
        if direction == "UP" {
            location.y + 1
        else if direction == "DOWN" {
            location.y - 1
        else if direction == "LEFT" {
            location.x + 1
        else if direction == "RIGHT" {
            location.x - 1

2 Answers

Hi there,

A few points on this.

FIrst, you might want to consider using a switch statement to handle the multiple options, rather than chaining a load of if statements together. There's a post about that here.

Secondly, you aren't changing the value of the location components. Saying location.y + 1 doesn't increment location.y you either need to assign that back into location.y or use the unary increment operator, ++:

// assign the value to change it
location.y = location.y + 1

// or increment

You don't need to assign the result of the ++ operator - it works just fine like that.

Thirdly, I think the strings being input are capitalised initials, rather than ALL CAPS, so you may want to try testing for "Up" rather than "UP".

I hope that helps - let me kow how you get on.


Ling Cheng
Ling Cheng
3,168 Points

Thanks very much, I understand now.

No problem! :+1: