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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

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

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