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

Posted by heather wolfram
heather wolfram
1,594 Points

I have tried just about everything. Nothing will go through! Please help :)

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.

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.

robots.swift 
class Point {
    var x: Int
    var y: Int

    init(x: Int, y: Int){
        self.x = x
        self.y = y
    }
}

enum Direction {
    case Left
    case Right
    case Up
    case Down
}

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++
            case "Down" : location.y--
            case "Left" : location.x--
            case "Right" : location.x++
            default : break
            }
        }
}

1 Answer

Dan Lindsay
Dan Lindsay
39,611 Points
Dan Lindsay
Dan Lindsay
39,611 Points

Hi Heather,

You are so very close on this one. I believe that Swift 3 deprecated both ++ and --. If you change the move function in your Robot class to this:

 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
    }
  }

this should pass the challenge. I also notice that the challenge does not have the Direction enum like the code you posted above. Delete that as well if just changing the move function doesn't pass the challenge.

Hope this helps!

Dan