(of property: KeyPath) -> [String?] where P : ProgressManager.Property, P.Summary == [String?], P.Value == String? ``` ## Parameters `property` The type of the string property to summarize. Must be a property where both the value and summary types are `String`. ## Return Value The aggregated summary value for the specified property across the entire subtree. ## Discussion This method aggregates the values of a custom string property from the underlying progress manager and all its children, returning a consolidated summary 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)