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# CFBitVectorFlipBitAtIndex(_:_:)

Flips a bit value in a bit vector.

```
func CFBitVectorFlipBitAtIndex(_ bv: CFMutableBitVector!, _ idx: CFIndex)
```

## Parameters

`bv`

The bit vector to modify.

`idx`

The index of the bit value to flip. The index must be in the range `0…N-1`, where `N` is the count of the vector.

## See Also

[`CFBitVectorGetCount(_:)`](/documentation/CoreFoundation/CFBitVectorGetCount(_:))

Returns the number of bit values in a bit vector.


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