Computed properties

We just created a Sport struct like this:

struct Sport {
    var name: String
}

That has a name property that stores a String. These are called stored properties, because Swift has a different kind of property called a computed property – a property that runs code to figure out its value.

We’re going to add another stored property to the Sport struct, then a computed property. Here’s how that looks:

struct Sport {
    var name: String
    var isOlympicSport: Bool

    var olympicStatus: String {
        if isOlympicSport {
            return "\(name) is an Olympic sport"
        } else {
            return "\(name) is not an Olympic sport"
        }
    }
}

As you can see, olympicStatus looks like a regular String, but it returns different values depending on the other properties.

We can try it out by creating a new instance of Sport:

let chessBoxing = Sport(name: "Chessboxing", isOlympicSport: false)
print(chessBoxing.olympicStatus)

Save 50% on all books and bundles

The biggest ever Hacking with Swift sale is now on, letting you save 50% on all books and bundles. Learn something new with Swift and enjoy great savings while the sale lasts!

Click here to save 50% in our Black Friday sale!