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 2.0 Getting Started with iOS Development Swift Recap Part 2

Moving method

Not working, wonder why?

Challenge Task 1 of 1

In the editor you've been provided with two classes - Point to represent a coordinate point and Machine. The machine has a move method that doesn't do anything because most machines are motionless.

Your task is to subclass Machine and create a new class named Robot. In the Robot class, override the move method and provide the following implementation. If you enter the string "Up" the y coordinate of the Robot's location increases by 1. "Down" decreases it by 1. If you enter "Left", the x coordinate of the location property decreases by 1 while "Right" increases it by 1.

Note: If you use a switch statement you can use the break statement in the default clause to exit the current iteration

./Users/mattconway/Desktop/Screen Shot 2016-01-30 at 12.51.49 PM.png

classes.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 func move(direction: String) {
    let move = ["Up", "Down", "Left", "Right"]
    let direction = location
    switch move {
      case "Up": Point(y + 1)
      case "Down": Point(y - 1)
      case "Left": Point(x - 1)
      case "Right": Point(x + 1)
      default: break
    }
  }
}

6 Answers

Matt,

Try this one.

class Robot: Machine {
    override func move(direction: String) {
        switch(direction) {
            case "Up":
                self.location.y++
            case "Down":
                self.location.y--
            case "Left":
                self.location.x--
            case "Right":
                self.location.x++
            default:
                break
        }
    }
}

Florin

Matt,

When the move method is called, the "direction" variable will be equal to either "Up", "Down", "Left" or "Right".

You will need to switch on the "direction" variable, not on the move variable, then, if it is equal to "Up", increase self.location.y by one, if equal to "Down", decrease self.location.y, if equal to "Left" decrease self.location.x by one, and if equal to "Right" increase self.location.x by one.

You do not need the "move" array or to change the value of the "direction" variable.

Let me know if you need more help.

Florin

Not really working for me. I thought you use "self.location.y" if you have a init, and you need to use "case" for a switch statement.

Yeah, it worked. I was confused in some area. Thanks for pointing out.

Dangelot Muzeau
Dangelot Muzeau
892 Points

what's the answer I'm stuck for hours in this, Please help ?

Stuck for hours? I've been stuck on this one for days. I've read countless forums and used many other's proposed methods and not a single one has worked. It makes me wonder if this challenge is bugged?