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iOS Object-Oriented Swift Properties Getter and Setter Methods

Posted by Michael McKinley
Michael McKinley
1,476 Points

Can someone help me with this code?

Pretty lost.

We need to add getter and setter methods to the fahrenheit property of the Temperature class. Add a getter method to the access the value of the fahrenheit property. Then add a setter method. When the user assigns a value to the fahrenheit property, the setter method will calculate and assign a value to the celsius property. (Note: Celsius = (Fahrenheit-32)/1.8))

Temperature.swift 
class Temperature {
    var celsius: Float = 0.0
    var fahrenheit: Float {
      get {
        return (celsius * 1.8) + 32.0
    }    
    set {
        fahrenheiht = newValue
        celsius = (fahrenheit - 32)/1.8))
}
}
Bradan Jackson
Bradan Jackson
20,558 Points
Bradan Jackson
Bradan Jackson
20,558 Points

I believe that should work, but you have an extra "h" in Fahrenheit, when you're setting Fahrenheit to the new value. Also, you have two close parentheses at the end of that statement that should not be there.

The code I used for the setter method was just celsius = (newValue - 32)/1.8

2 Answers

J.D. Sandifer
J.D. Sandifer
18,813 Points
J.D. Sandifer
J.D. Sandifer
18,813 Points

Expanding a little on Kyle's great answer: You're never going to assign a value directly to a computed property. Remember, a computed property is just that, one that's computed based on other properties. It never has a stored value - it's simply re-calculated each time it's accessed. Setter methods change values on the other properties that the computed property references, thus changing what's returned when the computed value is accessed.

The challenge is an excellent example of why these properties are useful. We might want to talk about a temperature using either Celsius or Fahrenheit depending on who's using our app, but we only want to store one value. We can access the correct value and change that value using either temperature scale.

kjvswift93
kjvswift93
13,515 Points
kjvswift93
kjvswift93
13,515 Points

The correct answer is this: 

class Temperature {
    var celsius: Float = 0.0
    var fahrenheit: Float {
        get {
            return (celsius * 1.8) + 32.0
        }
        set {
            celsius = (newValue-32)/1.8

        }
    }


}

We only need to set the celsius variable it's equivalent fahrenheit value by using the conversion equation. No need to assign fahrenheit to it's own new value .