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Introduced in iOS 26, the backgroundExtensionEffect modifier in SwiftUI enables developers to extend a view’s visual content beyond its safe area by creating mirrored copies with a blur effect. This article explains the functionality of the modifier and provides an example of its implementation in a SwiftUI application.

Overview of backgroundExtensionEffect

The backgroundExtensionEffect modifier duplicates a view into mirrored copies, placing them around the original view on any edge with available safe area space. A blur effect is applied over these copies to create a seamless, immersive background. This modifier is particularly useful in scenarios such as a navigation split view, where a view in the detail column can extend under the sidebar or inspector to maintain visual continuity. The modifier automatically clips the view to prevent overlapping copies, ensuring a clean presentation.

Implementing backgroundExtensionEffect

The following example demonstrates how to apply the backgroundExtensionEffect modifier to an image within a SwiftUI view. The image fills the available space and extends into the safe area with mirrored, blurred copies:

import SwiftUI

struct ContentView: View {
    var body: some View {
        GeometryReader {
            let size = $0.size
            let width = size.width
            let height = size.height
            
            Image(.nature)
                .resizable()
                .scaledToFill()
                .frame(width: width, height: height)
                .backgroundExtensionEffect()
        }
    }
}

In this code, the GeometryReader retrieves the dimensions of the parent view to ensure the image fills the available space. The Image is set to a predefined asset (.nature), scaled to fill the frame, and the backgroundExtensionEffect modifier is applied. This creates mirrored copies of the image around the safe area edges, with a blur effect to soften the transitions. The result is a visually cohesive background suitable for overlaying other content, such as in a navigation split view’s detail column.

Conclusion

The backgroundExtensionEffect modifier provides a mechanism to extend a view’s content beyond its safe area, creating mirrored, blurred copies for a seamless background. By applying this modifier, developers can enhance the visual integration of backgrounds in layouts such as navigation split views, ensuring continuity across different regions of the interface.