---
title: "MACaptionAppearanceGetWindowOpacity(_:_:)"
framework: mediaaccessibility
role: symbol
role_heading: Function
path: "mediaaccessibility/macaptionappearancegetwindowopacity(_:_:)"
---

# MACaptionAppearanceGetWindowOpacity(_:_:)

Returns the preference for the overlay’s opacity.

## Declaration

```swift
func MACaptionAppearanceGetWindowOpacity(_ 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 The float value, ranging from 0.0 to 1.0, representing the opacity of the color behind all other caption elements.

## See Also

### Caption window settings

- [MACaptionAppearanceCopyWindowColor(_:_:)](mediaaccessibility/macaptionappearancecopywindowcolor(_:_:).md)
- [MACaptionAppearanceGetWindowRoundedCornerRadius(_:_:)](mediaaccessibility/macaptionappearancegetwindowroundedcornerradius(_:_:).md)