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

Posted by Raju Ramesh
Raju Ramesh
307 Points

Methods

Can anyone please give me the code because it's a bit confusing to me.

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!")
  }
}

class Robot: Machine {

2 Answers

Dhanish Gajjar
Dhanish Gajjar
20,185 Points
Dhanish Gajjar
Dhanish Gajjar
20,185 Points

You should try to go back and understand the concepts clearly. Below is the code. Hope it helps you understand.

class Robot:Machine {

    override func move(_ direction: String) {

        switch direction {
        case "Up": location.y += 1
        case "Down": location.y -= 1
        case "Left": location.x -= 1
        case "Right": location.x += 1
        default: break
        }
    }
}
Raju Ramesh
Raju Ramesh
307 Points

When to use underscore in function parameter brackets??

Dhanish Gajjar
Dhanish Gajjar
20,185 Points
Dhanish Gajjar
Dhanish Gajjar
20,185 Points

Raju Ramesh The _ is used when you want to omit the external name for an argument. I strongly recommend visiting older videos where Pasan explains that arguments in swift can have 2 names, external and internal.

If the external name is not omitted, when you call the function move on an instance of a Robot 

let robot = Robot()
robot.move(direction: "Up")

It would read like move ( direction : up )

whereas If it is omitted using an _

let robot = Robot()
robot.move("Up")

This would read like move up. It is not mandatory to always omit the external name. It is what shows up as a label when you call the function. By omitting it, direction becomes the internal name, which you can use within the function, but it won't show up elsewhere.

Hope it's not too confusing, and I have made it clear.