# ??(_:_:) Performs a nil-coalescing operation, returning the wrapped value of an `Optional` instance or a default value. ``` func ?? (optional: consuming T?, defaultValue: @autoclosure () throws -> T) rethrows -> T where T : ~Copyable ``` ## Parameters `optional` An optional value. `defaultValue` A value to use as a default. `defaultValue` is the same type as the `Wrapped` type of `optional`. ## Discussion A nil-coalescing operation unwraps the left-hand side if it has a value, or it returns the right-hand side as a default. The result of this operation will have the non-optional type of the left-hand side’s `Wrapped` type. This operator uses short-circuit evaluation: `optional` is checked first, and `defaultValue` is evaluated only if `optional` is `nil`. For example: ``` func getDefault() -> Int { print("Calculating default...") return 42 } let goodNumber = Int("100") ?? getDefault() // goodNumber == 100 let notSoGoodNumber = Int("invalid-input") ?? getDefault() // Prints "Calculating default..." // notSoGoodNumber == 42 ``` In this example, `goodNumber` is assigned a value of `100` because `Int("100")` succeeded in returning a non-`nil` result. When `notSoGoodNumber` is initialized, `Int("invalid-input")` fails and returns `nil`, and so the `getDefault()` method is called to supply a default value. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)