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# CGDisplayIsInMirrorSet(_:)

Returns a Boolean value indicating whether a display is in a mirroring set.

```
func CGDisplayIsInMirrorSet(_ display: CGDirectDisplayID) -> boolean_t
```

## Parameters

`display`

The identifier of the display to be accessed.

## Return Value

If `true`, the specified display is a member of a software or hardware mirroring set; otherwise, `false`.

## Discussion

For more information about display mirroring, see [`CGConfigureDisplayMirrorOfDisplay(_:_:_:)`](/documentation/CoreGraphics/CGConfigureDisplayMirrorOfDisplay(_:_:_:)).

---

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