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iOS Object-Oriented Swift Properties Computed Properties

Posted by NOUR A ALGHAMDI
NOUR A ALGHAMDI
Courses Plus Student 5,607 Points

challenge 1 :\ unknown error!

good evening every one :) i tried to write the code that geven in the challenge but there still a mistake i wrote it as this : 

class Temperature {
    var Celsius: Float = 0.0
    var Fahrenheit: Float {
        return (Celsius * 1.8) + 32
    }
    init ( Celsius: Float){
        self.Celsius = Celsius
    }
}
let tump = Temperature (Celsius: 56.6)
tump.Fahrenheit

it showes me this error : You forgot to add a computed property named fahrenheit!

3 Answers

Steve Hunter
Steve Hunter
57,712 Points

HI there,

This is a tricky one, yes. Here's one solution for it:

class Temperature {
    var celsius: Float = 0.0
    var fahrenheit: Float {
        get {
            return (celsius * 1.8) + 32
        }
        set {
            celsius = (newValue - 32) / 1.8
        }
    }
}

I don't think you need the initializer in there for this challenge. You must compute the fahrenheit variable by backward engineering from the value of celsius.

NOUR A ALGHAMDI
NOUR A ALGHAMDI
Courses Plus Student 5,607 Points

ok thank you Steve , but i have a qustion here , what did i compute in my code ??

Steve Hunter
Steve Hunter
57,712 Points

HI there,

You mixed a variable declaration, var Fahrenheit: Float with a method. It wouldn't compile to anything, I wouldn't think.

Steve.

P.S. Only class names should be capitalised, I think, so your stored properties should be celsius and fahrenheit.

NOUR A ALGHAMDI
PLUS
NOUR A ALGHAMDI
Courses Plus Student 5,607 Points
NOUR A ALGHAMDI
NOUR A ALGHAMDI
Courses Plus Student 5,607 Points

ok one last question :) in the challenge he asked to assign read-only that means we have to do getter method without setter ! right ??

and i want to mention something i did what Mr.Amit done in previous video . . . 

class fuirnature : product {
    let hight: Double
    let width : Double
    let length : Double

    var surfaceArea: Double {
        return length * hight
    }

    init ( title: String , price: Double , hight: Double , width: Double , length: Double) {
        self.hight = hight
        self.width = width
        self.length = length
        super.init (title: title , price: price)
    }
}
let table = fuirnature (title: "coffee Table", price: 23, hight: 56, width: 67, length: 78)
table.surfaceArea

is it wrong ?! i mean i didn't anderstand what you mean by mix variable declaration with method!

thank you :)

SANGEETHA KURUNTHAIAH
SANGEETHA KURUNTHAIAH
1,947 Points
SANGEETHA KURUNTHAIAH
SANGEETHA KURUNTHAIAH
1,947 Points

Hi Nour, This challenge can be cracked as above..

 var celsius: Float = 0.0
  var fahrenheit: Float {
   return (celsius * 1.8) + 32   }

no need to use init here..