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

Matthew Ingram
PLUS
Matthew Ingram
Courses Plus Student 4,718 Points
Posted by Matthew Ingram
Matthew Ingram
Courses Plus Student 4,718 Points

Stuck on this

Need help I still dont have a great understanding of the statements involving overriding inits on subclasses need help figuring that out

robots.swift 
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 init(x: Int, y: Int) {
        super.init(self.x: x, self.y: y)

    }


    override func move(_ direction: String) {
        switch movement{
        case "Up":
            x += 1
        case "Down":
            x -= 1
        case "Right":
            y += 1
        case "Left":
            y -= 1

        default break
        }
    }
}

1 Answer

Anthony Lafont
Anthony Lafont
17,075 Points
Anthony Lafont
Anthony Lafont
17,075 Points

Hi Matthew,

By subclassing the Machine class, you will get an automatic inheritance of its initialization. As we don't need to modify it for our Robot subclass, it's ok not to mess with initialization in this case.

But we do want to override the move method, and you were close to the right answer. If you want to change the position of the class, you need to access the "x" property inside the "location" property like this:

location.x += 1

Here is the code:

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) {
        switch direction {
        case "Up":
            location.y += 1
        case "Down":
            location.y -= 1
        case "Right":
            location.x += 1
        case "Left":
            location.x -= 1
        default: break
        }
    }
}

Hope this helps! Anthony