# One A regex component that matches exactly one occurrence of its underlying component. ``` struct One

``` ## Relationships ### Conforms To [`RegexComponent`](/documentation/Swift/RegexComponent) --- 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)