# init(bitmapRepresentation:) Returns a character set containing characters determined by a given bitmap representation. ``` init(bitmapRepresentation data: Data) ``` ## Parameters `data` A bitmap representation of a character set. ## Return Value A character set containing characters determined by `data`. ## Discussion This method is useful for creating a character set object with data from a file or other external data source. A raw bitmap representation of a character set is a byte array with the first 2^16 bits (that is, 8192 bytes) representing the code point range of the the Basic Multilingual Plane (BMP), such that the value of the bit at position n represents the presence in the character set of the character with decimal Unicode value n. A bitmap representation may contain zero to sixteen additional 8192 byte segments to for each additional Unicode plane containing a character in a character set, with each 8192 byte segment prepended with a single plane index byte. To add a character in the Basic Multilingual Plane (BMP) with decimal Unicode value n to a raw bitmap representation, you might do the following: ```objc unsigned char bitmapRep[8192]; bitmapRep[n >> 3] |= (((unsigned int)1) << (n & 7)); ``` To remove that character: ```objc bitmapRep[n >> 3] &= ~(((unsigned int)1) << (n & 7)); ``` --- 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)