# subscript(_:) Gets the value for the subview that’s associated with the specified key. ``` subscript(key: K.Type) -> K.Value where K : LayoutValueKey { get } ``` ## Overview If you define a custom layout value using [`LayoutValueKey`](/documentation/SwiftUI/LayoutValueKey), you can read the key’s associated value for a given subview in a layout container by indexing the container’s subviews with the key type. For example, if you define a `Flexibility` key type, you can put the associated values of all the layout’s subviews into an array: ``` let flexibilities = subviews.map { subview in subview[Flexibility.self] } ``` For more information about creating a custom layout, see [`Layout`](/documentation/SwiftUI/Layout). --- 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)