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thiennc-tesoglobal/ios-skills

Community-maintained Agent Skills for complete Swift and Apple-platform app delivery.

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SKILL.mdskills/natural-language/

name:
natural-language
description:
Tokenize, tag, and analyze natural language text using Apple's NaturalLanguage framework and translate between languages with the Translation framework. Use when adding language identification, sentiment analysis, named entity recognition, part-of-speech tagging, text embeddings, or in-app translation to iOS/macOS/visionOS apps.

NaturalLanguage + Translation

Analyze natural language text for tokenization, part-of-speech tagging, named entity recognition, sentiment analysis, language identification, and embeddings using NaturalLanguage. Translate text with Translation. Targets Swift 6.3 / iOS 26+.

Contents

  • Framework Scope and Boundaries
  • Core Capabilities Matrix
  • Thread Safety and Performance
  • Translation Availability
  • Route by Task
  • Common Mistakes
  • Review Checklist
  • References

Framework Scope and Boundaries

  • NaturalLanguage: On-device text analysis (NLTokenizer, NLTagger, NLLanguageRecognizer, NLEmbedding, NLModel). Requires no special entitlements.
  • Translation: In-app UI and programmatic language translation (TranslationSession, LanguageAvailability).
  • Boundaries: Route OCR and image text recognition to vision-framework; route audio speech-to-text to speech-recognition; route generative LLM features to apple-on-device-ai; route static localization to ios-localization.

Core Capabilities Matrix

CapabilityPrimary ClassKey Output
TokenizationNLTokenizerSubstrings segmented by word, sentence, or paragraph
Language IDNLLanguageRecognizerNLLanguage (e.g. .english, .vietnamese) with confidence
Part of SpeechNLTagger (.lexicalClass)NLTag (.noun, .verb, .adjective, .pronoun)
Named EntitiesNLTagger (.nameType)Personal names, place names, organization names
SentimentNLTagger (.sentimentScore)Continuous score between -1.0 and +1.0
Semantic DistanceNLEmbeddingCosine distance and neighbor queries for words/sentences
System Translation.translationPresentation()Native system modal translation sheet
Batch TranslationTranslationSessionAsync batch translated strings

Thread Safety and Performance

[!IMPORTANT] NLTokenizer and NLTagger are not thread-safe. Do not share instances across concurrent tasks or queues. Create instances on demand or isolate them within a serial actor. NLEmbedding instances are read-only and thread-safe once loaded into memory.

Translation Availability

  • .translationPresentation(isPresented:text:): iOS 17.4+, macOS 14.4+, visionOS 1.1+
  • TranslationSession, .translationTask(), and LanguageAvailability: iOS 18.0+, macOS 15.0+, visionOS 2.0+
  • Offline programmatic translation via TranslationSession(installedSource:target:) requires the target language packs to be already installed on device.

Route by Task

  • For word/sentence tokenization, language recognition, and emoji/numeric detection, read Tokenization and Language ID.
  • For POS tagging, entity extraction, sentiment analysis, and embeddings, read Tagging and Embeddings.
  • For custom Core ML text classifiers and taggers with NLModel, read Custom NLModel Classifiers.
  • For SwiftUI translation sheets, batch translation, and language pack availability, read Translation Patterns.

Common Mistakes

  • Sharing an NLTokenizer or NLTagger across concurrent threads or Tasks without isolation.
  • Passing empty strings to NLEmbedding or checking similarity without unwrapping optionals.
  • Using TranslationSession offline when language packs are not installed on device.
  • Performing synchronous NLP tagging or sentence embedding on the main thread during UI scrolling.
  • Misinterpreting sentiment scores: scores range from -1.0 to 1.0 (0.0 is neutral, nil indicates untagged).

Review Checklist

  • NLTokenizer and NLTagger used from a single thread or isolated in an actor
  • Availability guards applied for TranslationSession (iOS 18+) vs presentation sheet (iOS 17.4+)
  • Language availability verified with LanguageAvailability.status() before programmatic translation
  • Long text analysis dispatched off @MainActor to background tasks
  • NLEmbedding.wordEmbedding(for:) checked for nil availability in the target language
  • Tag options include .omitWhitespace and .omitPunctuation where appropriate

References

skills

natural-language

SKILL.md

.mcp.json

README.md

tile.json