What Are Optionals

Sometimes a variable might not have a value at all. In Swift, we represent the absence of a value using optionals. An optional says "there is a value, and it equals x" or "there isn't a value at all."

To declare an optional, add a question mark ? after the type:

var nickname: String? = "Alex"
var age: Int? = nil

In the example above, nickname holds the value "Alex", while age holds nil — Swift's way of saying "no value." Regular variables cannot be nil, but optionals can.

Think of an optional as a box that might contain something or might be empty. Before using what's inside, you need to check if there's actually something there. This is a key safety feature in Swift that helps prevent crashes from unexpected missing values.

var score: Int? = 100
print(score) // Optional(100)

score = nil
print(score) // nil

Notice that when you print an optional with a value, it shows Optional(100) rather than just 100. To access the actual value inside, you need to unwrap the optional — which we'll cover in the upcoming lessons.