# layoutValue(key:value:) Associates a value with a custom layout property. ``` nonisolated func layoutValue(key: K.Type, value: K.Value) -> some View where K : LayoutValueKey ``` ## Parameters `key` The type of the key that you want to set a value for. Create the key as a type that conforms to the [`LayoutValueKey`](/documentation/SwiftUI/LayoutValueKey) protocol. `value` The value to assign to the key for this view. The value must be of the type that you establish for the key’s associated value when you implement the key’s [`defaultValue`](/documentation/SwiftUI/LayoutValueKey/defaultValue) property. ## Return Value A view that has the specified value for the specified key. ## Discussion Use this method to set a value for a custom property that you define with [`LayoutValueKey`](/documentation/SwiftUI/LayoutValueKey). For example, if you define a `Flexibility` key, you can set the key on a [`Text`](/documentation/SwiftUI/Text) view using the key’s type and a value: ``` Text("Another View") .layoutValue(key: Flexibility.self, value: 3) ``` For convenience, you might define a method that does this in an extension to [`View`](/documentation/SwiftUI/View): ``` extension View { func layoutFlexibility(_ value: CGFloat?) -> some View { layoutValue(key: Flexibility.self, value: value) } } ``` This method makes the call site easier to read: ``` Text("Another View") .layoutFlexibility(3) ``` If you perform layout operations in a type that conforms to the [`Layout`](/documentation/SwiftUI/Layout) protocol, you can read the key’s associated value for each subview of your custom layout type. Do this by indexing the subview’s proxy with the key. For more information, see [`LayoutValueKey`](/documentation/SwiftUI/LayoutValueKey). --- 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)