What is a computed property?
Swift offers us two kinds of property: a stored property is one that saves a value for use later, and a computed property is one that runs some code in order to calculate the value.
As comparison, here’s a Person struct with four stored properties and one computed one. The computed property returns a string based on joining the four stored properties into a sentence.
struct Person {
var name = "Taylor"
var favoriteColor = "red"
var favoriteCity = "Tokyo"
var favoriteFood = "tea"
var greeting: String {
return "Hello, my name is \(name), and I like \(favoriteFood), \(favoriteCity), and the color \(favoriteColor)."
}
}Note: Unlike stored properties, Swift requires you to use an explicit type with your computed properties.
Available from iOS 8.0
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