---
title: "CFBitVectorCreateMutableCopy(_:_:_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cfbitvectorcreatemutablecopy(_:_:_:)"
---

# CFBitVectorCreateMutableCopy(_:_:_:)

Creates a new mutable bit vector from a pre-existing bit vector.

## Declaration

```swift
func CFBitVectorCreateMutableCopy(_ allocator: CFAllocator!, _ capacity: CFIndex, _ bv: CFBitVector!) -> CFMutableBitVector!
```

## Parameters

- `allocator`: The allocator to use to allocate memory for the new object. Pass NULL or kCFAllocatorDefault to use the current default allocator.
- `capacity`: The maximum number of values that can be contained by the new bit vector. The bit vector starts with the same number of values as bv and can grow to this number of values (it can have less). Pass 0 to specify that the maximum capacity is not limited. If non-0, capacity must be large enough to hold all bit values from bv.
- `bv`: The bit vector to copy.

## Return Value

Return Value A new bit vector holding the same bit values as bv. Ownership follows the The Create Rule

## See Also

### Related Documentation

- [CFBitVectorSetCount(_:_:)](corefoundation/cfbitvectorsetcount(_:_:).md)

### Creating a CFMutableBitVector Object

- [CFBitVectorCreateMutable(_:_:)](corefoundation/cfbitvectorcreatemutable(_:_:).md)