Detect Language of NSString

Question

Somebody told me about a class for language recognition in Cocoa. Does anybody know which one it is?

This is not working:

NSSpellCh         


        

Answer 1

With Swift 5, you can choose one of the following approaches in order to detect the language of a given string.

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#1. Using NSLinguisticTagger's dominantLanguage property

Since iOS 11, NSLinguisticTagger has a property called dominantLanguage. dominantLanguage has the following declaration:

var dominantLanguage: String? { get }

Returns the dominant language of the string set for the linguistic tagger.

The Playground sample code below show how to use dominantLanguage in order to know the dominant language of a string:

import Foundation

let text = "あなたはそれを行うべきではありません。"
let tagger = NSLinguisticTagger(tagSchemes: [.language], options: 0)
tagger.string = text
let language = tagger.dominantLanguage
print(language) // Optional("ja")

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#2. Using NSLinguisticTagger's dominantLanguage(for:) method

As an alternative, NSLinguisticTagger has a convenience method called dominantLanguage(for:) for creating a new linguistic tagger, setting its string property and getting the dominantLanguage property. dominantLanguage(for:) has the following declaration:

class func dominantLanguage(for string: String) -> String?

Returns the dominant language for the specified string.

Usage:

import Foundation

let text = "Die Kleinen haben friedlich zusammen gespielt."
let language = NSLinguisticTagger.dominantLanguage(for: text)
print(language) // Optional("de")

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#3. Using NLLanguageRecognizer's dominantLanguage property

Since iOS 12, NLLanguageRecognizer has a property called dominantLanguage. dominantLanguage has the following declaration:

var dominantLanguage: NLLanguage? { get }

The most likely language for the processed text.

Here’s how to use dominantLanguage to guess the dominant language of natural language text:

import NaturalLanguage

let string = "J'ai deux amours. Mon pays et Paris."
let recognizer = NLLanguageRecognizer()
recognizer.processString(string)
let language = recognizer.dominantLanguage
print(language?.rawValue) // Optional("fr")