# buttonSizing(_:) The preferred sizing behavior of buttons in the view hierarchy. ``` nonisolated func buttonSizing(_ sizing: ButtonSizing) -> some View ``` ## Parameters `sizing` A button sizing behavior that may be used to influence the primary axis size of buttons capable of adapting to it. ## Discussion Views may use the specified button sizing when determining the size they choose to be in their primary axis within their parent view’s proposed size. Many built-in controls that display as a button adapt to this view modifier. For example, you can make certain styles of [`Button`](/documentation/SwiftUI/Button), [`Picker`](/documentation/SwiftUI/Picker), [`ControlGroup`](/documentation/SwiftUI/ControlGroup), and [`Toggle`](/documentation/SwiftUI/Toggle) flexible by applying this modifier to them or their container. This example creates a button that spans the width of its container, which you may want to do if the button is placed in a narrow context, like the sidebar of a welcome window. ``` Button("Open Document…", action: openDocument) .buttonSizing(.flexible) ``` Your own views and styles can adapt to this view modifier by reading the [`buttonSizing`](/documentation/SwiftUI/EnvironmentValues/buttonSizing) environment value and applying an appropriate frame. ``` struct CustomButtonStyle: ButtonStyle { @Environment(\.buttonSizing) private var buttonSizing private var maxWidth: CGFloat { switch buttonSizing { case .flexible: .infinity case .fitted, _: nil } } func makeBody(configuration: Configuration) -> some View { configuration.content .frame(maxWidth: maxWidth) .background(.tint, in: Capsule()) } } ``` --- 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)