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

Jarukorn Thuengjitvilas
Jarukorn Thuengjitvilas
1,357 Points

The code of point is wrong

The code of point is wrong

robots.swift
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":
            self.location = Point(x: location.getX(), y:location.getY()+1)

        case "Down":
            self.location = Point(x: location.getX(), y:location.getY()-1)

        case "Left":
            self.location = Point(x: location.getX()-1, y:location.getY())

        case "Right":
            self.location = Point(x: location.getX()+1, y:location.getY())
        default:
            break
        }
    }
}

1 Answer

Hi Jarukorn,

You've nearly got that - within each case you want to amend the location property of the Robot. So, if direction is "Right", you want to increment location.x. "Up" means you want to increment location.y. The reverse is the case for the other directions. Use += and -= to do the adjustment.

You end up with something like:

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
    }
  }
}

I hope that helps.

Steve.