Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

iOS Object-Oriented Swift Properties Getter and Setter Methods

Patricia Ortega
Patricia Ortega
3,322 Points

Assignment Problem

The assignment ask for:

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))

My solution is class Temperature { var celsius: Float = 0.0 var fahrenheit: Float { get { return fahrenheit } set { celsius = ((fahrenheit-32)/1.8) } } }

What is wrong? the check button only says "Try again" where is the mistake? the preview button does not show any error.

1 Answer

Nathan Tallack
Nathan Tallack
22,159 Points

Ok. A few things.

Firstly, the getter. Remember only the property celsius is a value type. The fahrenheit property is a computed property so it is not good to try and reference that for your getter. Better to use the celsius property for the getter on the computed property.

Secondly, the setter. You can't reference the celsius property here because that is an old value. You need to read in the new value. You could either declare the parameter name after the set, such as set(newTemp){}, or you could use use the default name newValue (part of syntactic sugar to help with shorthand setter declarations) as I have done in the example below.

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

Makes sense?