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

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
28,520 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.