---
title: UnicodeMapping
framework: Core Services
role: symbol
role_heading: Structure
platforms: [Mac Catalyst 17.0+, macOS 10.0+]
path: coreservices/unicodemapping
---

# UnicodeMapping

Contains information for mapping to or from Unicode encoding.

## Declaration

```occ
typedef struct UnicodeMapping {
    ...
} UnicodeMapping;
```

## Overview

Overview A Unicode mapping structure contains a complete text encoding specification for a Unicode encoding, a complete non-Unicode text encoding specification giving the encoding for the text to be converted to or from Unicode, and the version of the mapping table to be used for conversion. You use a structure of this type to specify the text encodings to and from which the text string is to be converted. A Unicode mapping structure is defined by the UnicodeMapping data type.  You can specify a variety of normalization options by setting up the Unicode mapping structure as described in the following. To specify normal canonical decomposition according to Unicode 3.2 rules, with no exclusions ("Canonical decomposition 3.2"), set up the UnicodeMapping structure as follows: mapping.unicodeEncoding (in) = Unicode 2.x-3.x, kUnicodeNoSubset,  kUnicode16BitFormat mapping.otherEncoding (out) = Unicode 2.x-3.x, kUnicodeCanonicalDecompVariant,  kUnicode16BitFormat mapping.mappingVersion = kUnicodeUseLatestMapping Examples: u00E0 -> u0061 + u0300 u0061 + u0300 -> u0061 + u0300 u03AC ->  u03B1 + u0301 (3.2 rules) uF900 -> u8C48 u00E0 + u0323 -> u0061 + u0323 + u0300  (correct) To specify canonical decomposition according to Unicode 3.2 rules, with HFS+ exclusions ("HFS+ decomposition 3.2"), set up the UnicodeMapping structure in one of the following ways. The second method is for compatibility with the old method of using mappingVersion = kUnicodeUseHFSPlusMapping. // Method 1 mapping.unicodeEncoding (in) = Unicode 2.x-3.x, kUnicodeNoSubset,  kUnicode16BitFormat mapping.otherEncoding (out) = Unicode 2.x-3.x, kUnicodeHFSPlusDecompVariant,  kUnicode16BitFormat mapping.mappingVersion = kUnicodeUseLatestMapping // Method 2 mapping.unicodeEncoding (in) = Unicode 2.x-3.x, kUnicode16BitFormat,  kUnicode16BitFormat mapping.otherEncoding (out) = Unicode 2.x, kUnicodeCanonicalDecompVariant,  kUnicode16BitFormat mapping.mappingVersion = kUnicodeUseHFSPlusMapping Examples: u00E0 -> u0061 + u0300 u0061 + u0300 -> u0061 + u0300 u03AC ->  u03B1 + u0301 (3.2 rules) uF900 -> uF900 (decomposition excluded for HFS+) u00E0 + u0323 -> u0061 + u0323 + u0300  (correct) To specify normal canonical composition according to Unicode 3.2 rules, set up the UnicodeMapping structure as follows: mapping.unicodeEncoding (in) = Unicode 2.x-3.x, kUnicodeNoSubset,  kUnicode16BitFormat mapping.otherEncoding (out) = Unicode 2.x-3.x, kUnicodeCanonicalCompVariant,  kUnicode16BitFormat mapping.mappingVersion = kUnicodeUseLatestMapping Examples: u00E0 -> u00E0 u0061 + u0300 -> u00E0 u03AC ->  u03AC uF900 -> u8C48 u00E0 + u0323 -> u1EA1 u0300 (correct) To specify canonical composition according to Unicode 3.2 rules, but using the HFS+ decomposition exclusions, set up the UnicodeMapping structure as follows. This is the form to use if you want to obtain a composed form that dervide from the decomposed form used for HFS+ filenames. mapping.unicodeEncoding (in) = Unicode 2.x-3.x, kUnicodeNoSubset,  kUnicode16BitFormat mapping.otherEncoding (out) = Unicode 2.x-3.x, kUnicodeHFSPlusCompVariant,  kUnicode16BitFormat mapping.mappingVersion = kUnicodeUseLatestMapping Examples: u00E0 -> u00E0 u0061 + u0300 -> u00E0 u03AC ->  u03AC uF900 -> uF900 u00E0 + u0323 -> u1EA1 u0300 (correct)

## Topics

### Instance Properties

- [mappingVersion](coreservices/unicodemapping/1433626-mappingversion.md)
- [otherEncoding](coreservices/unicodemapping/1433587-otherencoding.md)
- [unicodeEncoding](coreservices/unicodemapping/1433589-unicodeencoding.md)