# glassBackgroundEffect(_:displayMode:) Fills the view’s background with a custom glass background effect and container-relative rounded rectangle shape. ``` nonisolated func glassBackgroundEffect(_ effect: S, displayMode: GlassBackgroundDisplayMode = .always) -> some View where S : GlassBackgroundEffect ``` ## Parameters `effect` A [`GlassBackgroundEffect`](/documentation/SwiftUI/GlassBackgroundEffect) instance that SwiftUI uses to draw a background of the modified view. `displayMode` When to display the glass background. The default is [`GlassBackgroundDisplayMode.always`](/documentation/SwiftUI/GlassBackgroundDisplayMode/always). ## Return Value A view with a glass background. ## Discussion Use this modifier to add a glass material that may include thickness, specularity, glass blur, shadows, and other effects. Because of its physical depth, the background influences z-axis layout. For different effect, the background may influences x-axis and y-axis layout. To ensure that the effect renders properly when you add it to a collection of views in a [`ZStack`](/documentation/SwiftUI/ZStack), add the modifier to the stack rather to one of the views in the stack. This includes when you create an implicit stack with view modifiers like [`overlay(alignment:content:)`](/documentation/SwiftUI/View/overlay(alignment:content:)) or [`background(alignment:content:)`](/documentation/SwiftUI/View/background(alignment:content:)). In those cases, you might need to create an explicit [`ZStack`](/documentation/SwiftUI/ZStack) inside the `content` closure to have a place to add the background modifier. Non closed shapes will be rendered as their convex hull. --- 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)