Optional Values in Swift

Properties2

Type	Concept
Note created	Feb 17, 2025

In Swift, there are several ways to work with optional values, that is, values that be nil. A type is nullable if it suffixed with an interrogation, for example, let example: String?.

To unpack an optional value, we can use if let and guard let clauses, which assign the value to a constant.

• if let will provide the constant within a given scope to manipulate it.
• guard let will run the code provided if value is nil (for an early return).

Another way to deal with these kind of values is coalescing them, that is, providing a value to be used in case the given variable is null.

let unpacked = optional ?? 42

It is also important to know about chained optionals, where we call functions over optional types in case they are available. For example, this code:

var book: Book? = nil
let author = book?.author?.first?.uppercased() ?? "A"

Reads as “if there is a book, and it has an author, get me the first letter uppercased; otherwise return A”.