How to use get and install in Swift

Question

I have a simple code block calculating the area and perimeter of a rhombus.

 var perimeterOfRhombus: Double {
        get {
            let twoSides1 = sideLength1 + sideLength1
            let twoSides2 = sideLength2 + sideLength2
            let finalPerimeter = twoSides1 + twoSides2
            return finalPerimeter
        } set {
      }
    }

What I am missing is a section.

I want it to show which sideLength1 and sideLength2 were in the beginning.

I'm not sure what newValue is used for when it doesn't matter.

It works without using set, but I see in the Apple language manual swiftthat are installed and usually go together.

If the set is really not needed in this code, what is it usually used in any case?

Answer 1

Instead of calculated properties, you should refer to Computed Properties as read-only .

, , . .

 var perimeterOfRhombus: Double {
  let twoSides1 = sideLength1 + sideLength1
  let twoSides2 = sideLength2 + sideLength2
  let finalPerimeter = twoSides1 + twoSides2
  return finalPerimeter
 }

. .

, , , .

 struct Square {
  var edge: Double = 0

  var area: Double {
    get {
      return edge * edge
    }
    set (newArea){
      edge = sqrt(newArea)
    }
  }
 }

, , .

newValue, . , , newValue.

,

 struct Square {
  var edge: Double = 0

  var area: Double {
    get {
      return edge * edge
    }
    set {
      edge = sqrt(newValue) //someSquare.area = 25 (25 is newValue)
    }
  }
 }