# CFBitVectorCreate(_:_:_:) Creates an immutable bit vector from a block of memory. ``` func CFBitVectorCreate(_ allocator: CFAllocator!, _ bytes: UnsafePointer!, _ numBits: CFIndex) -> CFBitVector! ``` ## Parameters `allocator` The allocator to use to allocate memory for the new bit vector. Pass `NULL` or kCFAllocatorDefault to use the current default allocator. `bytes` A pointer to the bit values to store in the new bit vector. The values are copied into the bit vector’s own memory. The bit indices are numbered left-to-right with `0` being the left-most, or most-significant, bit in the byte stream. `numBits` The number of bits in the bit vector. ## Return Value A new bit vector. Ownership follows the [The Create Rule](https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html#//apple_ref/doc/uid/20001148-103029). ## Discussion --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)