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 Getting Started with iOS Development Swift Recap Part 2

Failed to compile overriding empty function

I'm not sure what I'm missing with this code challenge. Workspace won't compile but I don't get an error message to identify problem.

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 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 selection")
      break
    }
  }
}

1 Answer

Steven Deutsch
Steven Deutsch
21,046 Points

Hey Noe Arzate,

You're close but you don't need to override the initializer. You're not adding any new properties to the Robot class, you're only overriding the move method. Therefore, you can use the initializer you inherit from the Machine class.

Second, for the default statement in the move method, just break and don't print anything to the console. Remember we have to use a default case here since switch statements must be exhaustive and there are limitless combinations of strings. We use break inside the default statement to state we don't want to do anything in the case of any other string.

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!")
  }

}

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
      }
  }
}

EDIT: I noticed this challenge omits the external parameter name for the move method and have updated my code to do the same. It's best not to edit the code provided by the challenge.

Good Luck

Thank you for your help, very much appreciated.