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

Posted by Derrick Hoff
Derrick Hoff
9,385 Points

whats wrong with my override function move

the error message I keep getting when I look at the preview is :

swift_lint.swift:33:19: error: argument names for method 'move(direction:)' do not match those of overridden method 'move' override func move(direction: String) {

with an arrow pointing at the "m" what am I doing wrong I tried Capitalizing it but that didn't work either?

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! I'm a machine!")
  }
}

// Enter your code below

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

1 Answer

andren
andren
28,558 Points
andren
andren
28,558 Points

When you override a method the declaration has to be 100% identical. The original move method has an external parameter name of _. In your method you do not specify an external parameter name.

If you fix that by specifying _ as the external parameter name in your own move method like this:

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) { // <- Added _ as external parameter name
        switch direction {
        case "Up": self.location.y += 1
        case "Down": self.location.y -= 1
        case "Left": self.location.x -= 1
        case "Right": self.location.x += 1
        default: break
        }
    }
}

Then your code will work.