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

isaac brakha
isaac brakha
6,781 Points

Why is my code wrong Challenge Build iphone app

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 init() {

    self.location = location
    func move(_ direction: String) {
        let direction: String


        switch true {
          case direction == "Up": self.location.y += 1
          case direction == "Down": self.location.y -= 1
          case direction == "Left": self.location.x -= 1
          case direction == "Right": self.location.x += 1
          default: print("Bye")


        }

    }


}

}

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 am a machine!")
  }
}

// Enter your code below

class Robot: Machine {

    override init() {

        self.location = location
        func move(_ direction: String) {
            let direction: String


            switch true {
              case direction == "Up": self.location.y += 1
              case direction == "Down": self.location.y -= 1
              case direction == "Left": self.location.x -= 1
              case direction == "Right": self.location.x += 1
              default: print("Bye")


            }

        }


    }

}

1 Answer

There are a few reasons.

  1. Since you are overriding the init method, you will need to call super.init() before you can do anything else.
  2. You initialize the constant direction when you call the move function, so you cannot initialize it again with the let direction: String line.
  3. You will need to pass the direction constant into the switch statement rather than true.
  4. Once you correct #3, each case in the switch statement already does the equivalent comparison so there is no need to have "direction ==" in any of the cases listed.

The correct code should be:

override init() {

        super.init()
        self.location = location

        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: print("Bye")

            }
        }
    }