# init(_:) Creates a regex component that chooses exactly one of the regex components provided by the builder closure. ``` init(@AlternationBuilder _ builder: () -> ChoiceOf

) ``` ## Parameters `builder` A builder closure that declares a list of regex components, each of which can be exclusively matched. ## Discussion In this example, `regex` successfully matches either a `"CREDIT"` or `"DEBIT"` substring: ``` let regex = Regex { ChoiceOf { "CREDIT" "DEBIT" } } let match = try regex.prefixMatch(in: "DEBIT 04032020 Payroll $69.73") print(match?.0 as Any) // Prints "DEBIT" ``` --- 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)