Structure

NSLinguisticTagScheme

Constants for the tag schemes specified when initializing a linguistic tagger.

Declaration

struct NSLinguisticTagScheme

Overview

When initializing a linguistic tagger with init(tagSchemes:options:), you specify one or more tag schemes that correspond to the kind of information you're interested in for a selection of natural language text. To ensure optimal performance, avoid specifying tag schemes that you won't use.

Some tag schemes are only available for certain units and languages. Use the availableTagSchemes(for:language:) or availableTagSchemes(forLanguage:) methods to determine the possible values for a specified language and linguistic unit.

When working with linguistic tags using the methods described in Getting Linguistic Tags and Enumerating Linguistic Tags, the returned tag value depends on the specified scheme. For example, given the token "Überraschung", the returned tag is noun when using the lexicalClass tag scheme, "de" (German language) when using the language tag scheme, and "Latn" (Latin script) when using the script tag scheme, as shown in the following code.

let tagger = NSLinguisticTagger(tagSchemes: [.lexicalClass, .language, .script], options: 0)
tagger.string = "Überraschung"

tagger.tag(at: 0, unit: .word, scheme: .lexicalClass, tokenRange: nil) // Noun
tagger.tag(at: 0, unit: .word, scheme: .language, tokenRange: nil) // de
tagger.tag(at: 0, unit: .word, scheme: .script, tokenRange: nil) // Latn

The following table lists the available tag schemes, their applicable linguistic units, and possible tag values.

Topics

Schemes

static let tokenType: NSLinguisticTagScheme

Classifies tokens according to their broad type: word, punctuation, or whitespace.

static let lexicalClass: NSLinguisticTagScheme

Classifies tokens according to class: part of speech, type of punctuation, or whitespace.

static let nameType: NSLinguisticTagScheme

Classifies tokens according to whether they are part of a named entity.

static let nameTypeOrLexicalClass: NSLinguisticTagScheme

Classifies tokens corresponding to names according to nameType, and classifies all other tokens according to lexicalClass.

static let lemma: NSLinguisticTagScheme

Supplies a stem form of a word token, if known.

static let language: NSLinguisticTagScheme

Supplies the language for a token, if one can be determined.

static let script: NSLinguisticTagScheme

Supplies the script for a token, if one can be determined.

Relationships

See Also

Supporting Types

enum NSLinguisticTaggerUnit

Constants representing linguistic units.

struct NSLinguisticTag

A token, lexical class, name, lemma, language, or script returned by a linguistic tagger for natural language text.