# subscript(dynamicMember:) Returns an attribute value that a key path indicates. ``` @preconcurrency subscript(dynamicMember keyPath: KeyPath) -> K.Value? where K : AttributedStringKey, K.Value : Sendable { get set } ``` ## Discussion This subscript returns `nil` unless the specified attribute exists, and is present and identical for the entire attributed string or substring. To find portions of the string with consistent attributes, use the [`runs`](/documentation/Foundation/AttributedString/runs-swift.property) property. Getting or setting stringwide attributes with this subscript has `O(n)` behavior in the worst case, where `n` is the number of runs. --- 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)