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iOS Object-Oriented Swift Properties Getter and Setter methods

Jake Sackman
Jake Sackman
1,922 Points

newValue??

Why did the newValue automatically set to 144 and not the values defined in the instance?

What I'm really trying to ask is why did Amit have to sqrt?

Any help would be appreciated

2 Answers

Jhoan Arango
Jhoan Arango
14,575 Points

Hello there

  • Computed Properties

“In addition to stored properties, classes, structures, and enumerations can define computed properties, which do not actually store a value. Instead, they provide a getter and an optional setter to retrieve and set other properties and values indirectly.”

Excerpt From: Apple Inc. “The Swift Programming Language (Swift 2 Prerelease).” iBooks. https://itun.es/us/k5SW7.l

So we know that a computed property is just a read-only property, where you can’t capture the value and use it somewhere else, it ONLY computes something and displays it (if you can say it like that).

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

var temp = Temperature()

temp.fahrenheit = 89 // newValue being passed

In this challenge in order of us to set a value to the celsius property we can use the newValue keyword, this will set the value passed through the fahrenheit computed property.

Hope you understand a bit more.

Where does the 89 come from?

Thank you SO much!