# subscript(_:) Returns the context’s value for a key, or a the key’s default value if the context doesn’t define a value for the key. ``` subscript(key: Key.Type) -> Key.Value where Key : PreviewContextKey { get } ``` --- 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)