Swift re-cap part 2.

Here is my solution:

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 am a machine!")
  }
}

// Enter your code below
class Robot: Machine {

  override func move(_ direction: String) {
    switch direction {
      case "Up": return location.y += 1
      case "Down": return location.y -= 1
      case "Left": return location.x -= 1
      case "Right": return location.x += 1
      default: break
    }
  }

}

Can someone explain why there is no init - super init needed with creating the Robot sub-class? Thank you

You want to create a new class, Robot, that inherits from the Machine class and overrides the move method that comes with the Machine class.

so basically:

class Robot: Machine {
    override func move() {
        //whatever
    }
}

check out the following link for some clear examples of subclassing and overriding: https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Inheritance.html

My immediate suspicion is scoping issues. Try self.x in the switch case.

Almost sure

I see a couple of things that should help you. Make sure you properly override the move function:

func override move(direction: String) {
}

Your switch control expression should be "direction" rather than "location" since "Up, Down, Right, and Left" are the directions.

Also try location.y instead of just y.

Hopefully this helps you.

Robert Cadorette thats a good point

i think there need to be some changes to the given code as well as the new

-------------given code needs-------------

class Machine {
  var location: Point
// var direction: String ///

  init() {
    self.location = Point(x: 0, y: 0)
 // not sure what code would in be used here//
  }

  func move(_ direction: String) {
    print("Do nothing! I am a machine!")
  }
}

--------------------new code--------------------

/// the code need to do///
///direction = location(move)///
/// for example "Up" = (location(x: 0, y: 0) + y: 1)///
/// the switch case would give the value the class would change to///

Using a switch statement is probably a good way to go for this challenge; however, I'm providing an alternative answer below for those wanting to solve this using an 'if' statement:

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 am a machine!")
  }
}

class Robot: Machine {

  override func move(_ direction: String) {
    if direction == "Up" {
            self.location.y += 1
    } else if direction == "Down" {
            self.location.y -= 1
    } else if direction == "Left" {
            self.location.x -= 1
    } else if direction == "Right" {
            self.location.x += 1
    } else {
            self.location = location
    }
  }
}

Random question, why is it that when I put

''' case "Up": y += 1 '''

versus

''' case "Up": location.y += 1'''

The first fails while the second succeeds? is it related to scope? The only reasoning I can really piece together is that x and y exist as variables within point, but inside the class Machine they only exist within location and Point, therefore they cannot be altered as individual variables. However, if we tried to alter them within the class Point, or simply outside any sort of object it would work? Trying to get a handle on scope and classes in general, any explanation or help is appreciated. Thanks in advanced.