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

Posted by Diogo Henriques
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Diogo Henriques
iOS Development Techdegree Student 8,035 Points

Your task is to subclass Machine and create a new class named Robot. In the Robot class, override the move method and pr

I don't know where is the mistake, i had look at the preview and i can't find to!

Can anyone tell me where is the mistake please?

Cheers !

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! Im a machine!")
        }
    }

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
            }
        }
}

1 Answer

Dhanish Gajjar
Dhanish Gajjar
20,185 Points
Dhanish Gajjar
Dhanish Gajjar
20,185 Points

Happens a lot to everyone. As you must have noticed there is a _ before the argument "direction". It is meant for omitting the external name. It is necessary, since the code editor is very specific about the challenges. So while your code is correct, it is must to have to Machine class, so the Robot also inherits it.

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 "Left": location.x -= 1
        case "Right": location.x += 1
        default: break
        }
    }
}