Extending optionals in Swift

Quick tip on how to extend an optional in Swift

16 May 2021 · 2 min read

swift

basics

Natascha Fadeeva

Author and creator of this site

As we have learned in Understanding Swift Optionals, an optional is just an enum of two cases.

enum Optional<Wrapped> {
    /// The absence of a value.
    case none

    /// The presence of a value, stored as `Wrapped`.
    case some(Wrapped)
}

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Knowing this, we can extend an optional just like any other type.

extension Optional where Wrapped == String {
    var isNilOrEmpty: Bool {
        return self?.isEmpty ?? true
    }
}

In the example above, we are extending an optional String by adding where Wrapped == String to our extension.

Now, we can use the computed property isNilOrEmpty on every optional String.

var name: String?
if name.isNilOrEmpty {
}

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