---
title: "backgroundPreferenceValue(_:_:)"
framework: swiftui
role: symbol
role_heading: Instance Method
path: "swiftui/view/backgroundpreferencevalue(_:_:)"
---

# backgroundPreferenceValue(_:_:)

Reads the specified preference value from the view, using it to produce a second view that is applied as the background of the original view.

## Declaration

```swift
nonisolated func backgroundPreferenceValue<Key, T>(_ key: Key.Type = Key.self, @ContentBuilder _ transform: @escaping (Key.Value) -> T) -> some View where Key : PreferenceKey, T : View

```

## Parameters

- `key`: The preference key type whose value is to be read.
- `transform`: A function that produces the background view from the preference value read from the original view.

## Return Value

Return Value A view that layers a second view behind the view.

## See Also

### Generating backgrounds and overlays from preferences

- [backgroundPreferenceValue(_:alignment:_:)](swiftui/view/backgroundpreferencevalue(_:alignment:_:).md)
- [overlayPreferenceValue(_:_:)](swiftui/view/overlaypreferencevalue(_:_:).md)
- [overlayPreferenceValue(_:alignment:_:)](swiftui/view/overlaypreferencevalue(_:alignment:_:).md)