---
title: "MACaptionAppearanceGetBackgroundOpacity(_:_:)"
framework: mediaaccessibility
role: symbol
role_heading: Function
path: "mediaaccessibility/macaptionappearancegetbackgroundopacity(_:_:)"
---

# MACaptionAppearanceGetBackgroundOpacity(_:_:)

Returns the preference for the text highlight opacity.

## Declaration

```swift
func MACaptionAppearanceGetBackgroundOpacity(_ domain: MACaptionAppearanceDomain, _ behavior: UnsafeMutablePointer<MACaptionAppearanceBehavior>?) -> CGFloat
```

## Parameters

- `domain`: The domain to retrieve the preference value from. See doc://com.apple.mediaaccessibility/documentation/MediaAccessibility/MACaptionAppearanceDomain. Pass doc://com.apple.mediaaccessibility/documentation/MediaAccessibility/MACaptionAppearanceDomain/user unless the system defaults are needed for comparison.
- `behavior`: A pointer to memory. On return, this memory holds the caption appearance behavior for this preference setting. For possible values see doc://com.apple.mediaaccessibility/documentation/MediaAccessibility/MACaptionAppearanceBehavior. Pass NULL when you do not need the behavior setting.

## Return Value

Return Value A float value, ranging from 0.0 to 1.0, representing the opacity of the color behind the text and above the window color.

## See Also

### Text highlight settings

- [MACaptionAppearanceCopyBackgroundColor(_:_:)](mediaaccessibility/macaptionappearancecopybackgroundcolor(_:_:).md)