How to detect the dominant language of a text string

Paul Hudson    September 20th 2017    @twostraws

The NSLinguisticTagger class has dedicated code to help you identify the dominant language of a text string. Before I show you the code, there are three important provisos:

1. It detects the dominant language, which means if you provide it with text that contains more than one language it will return whichever one appears most often.
2. If you give it text where no identification can be made, e.g. some numbers or an empty string, it will return nil.
3. It is extraordinarily fast – you can feed it thousands of article-length strings a second and it will fly through them.

Here’s an example to help you get started:

let text = "Ceci n'est pas une pipe"

if let language = NSLinguisticTagger.dominantLanguage(for: text) {
    print(language)
} else {
    print("Unknown language")
}

When that code runs it will print “fr”, because the dominant language in the text is French.

Available from iOS 11.0

Did this solution work for you? Please pass it on!

Tweet

Other people are reading…

• How to run code asynchronously using GCD async()
• How to format dates with an ordinal suffix using NumberFormatter's ordinalStyle
• How to read the contents of a directory using FileManager
• How to post messages using NotificationCenter
• How to use Touch ID to authenticate users by fingerprint

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.