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iOS Build a Simple iPhone App with Swift 2.0 Getting Started with iOS Development Architecture of an iOS App

Posted by Jacob Carroll
Jacob Carroll
5,957 Points

Code Challenge: Swift Recap Part: 2 (HELP)

Dear Answers,

Can some help me understand how to solve this?

As my mind is rusty with this type of info.

Thanks, JC

1 Answer

Miguel Angel Flores Izquierdo
Miguel Angel Flores Izquierdo
2,275 Points
Miguel Angel Flores Izquierdo
Miguel Angel Flores Izquierdo
2,275 Points 
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! Im a machine!")
    }
}
class Robot: Machine{

    override init()
    {
        super.init()
        self.location = Point(x: 0, y: 0)
    }
    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:
            print("Not a valid command!")
            break
        }

    }
}

this is my solution to the challenge, basically you got to create the subclass Robot, then as we know there are 2 steps in creating a subclass

  1. initialize all subclass properties (in this case Robot)
  2. initialize all superclass properties (in this case Machine)

since i did not add any properties the "override init()" just initializes the properties from Machine that is the location property.

the task is to override the Move method (also called function) on the Robot subclass so we call the method "override func move(direction: String) {". then proceed to add the code to move the location of the robot depending the value of an String var called "direction". if it goes "Up", Y value of location increases by 1 and a "Down" value decreases the value of Y by 1.

you cant test this code in a playground (i used Xcode 7.3) adding these lines below the code

var robot = Robot ()
robot.location
robot.move("Up")
robot.location
Niilo Pirttijärvi
Niilo Pirttijärvi
Courses Plus Student 2,354 Points
Niilo Pirttijärvi
Niilo Pirttijärvi
Courses Plus Student 2,354 Points

Hi, Could you open up a little bit what this part of the code does and especially why is it needed? override init() { super.init() self.location = Point(x: 0, y: 0) } Since the subclass Robot inherits everything from superclass Machine, why does it not inherit its location and initialisation as well?