speech-recognition

name speech-recognition description Transcribe speech to text using Apple's Speech framework. Use when implementing live microphone transcription with AVAudioEngine, recognizing recorded audio files, handling speech and microphone authorization, choosing on-device vs server-backed SFSpeechRecognizer behavior, or adopting SpeechAnalyzer, SpeechTranscriber, DictationTranscriber, AssetInventory, and async result streams on iOS 26+. Speech Recognition Transcribe live and pre-recorded audio to text using Apple's Speech framework. Covers SpeechAnalyzer / SpeechTranscriber (iOS 26+) and SFSpeechRecognizer (iOS 10+) fallback guidance. Scope boundary: Use this skill for speech-to-text recognition, speech authorization, microphone capture plumbing, and result handling. Hand off text analysis, language identification after transcription, sentiment, embeddings, and translation to natural-language ; hand off audio playback UI to avkit ; hand off summarization or generation over transcripts to apple-on-device-ai . Contents SpeechAnalyzer Strategy (iOS 26+) SFSpeechRecognizer Setup Authorization Live Microphone Transcription Pre-Recorded Audio File Recognition On-Device vs Server Recognition Handling Results Common Mistakes Review Checklist References SpeechAnalyzer Strategy (iOS 26+) Use SpeechAnalyzer for modern iOS 26+ speech analysis, especially long-form recordings, live transcription, time-indexed transcripts, and fully on-device flows. Keep SFSpeechRecognizer for iOS 10+ deployment targets, server-backed locale coverage, or existing callback/delegate implementations. Read SpeechAnalyzer patterns when implementing an iOS 26+ transcription pipeline, model asset handling, volatile results, or file/buffer examples. SpeechAnalyzer setup checklist Choose the module: SpeechTranscriber for the newer general-purpose on-device model. DictationTranscriber when SpeechTranscriber is unavailable for the current device or locale and dictation-compatible support is acceptable. SpeechDetector only in conjunction with a transcriber when voice activity detection is worth the accuracy/power tradeoff. Check support before creating the session: SpeechTranscriber.isAvailable SpeechTranscriber.supportedLocale(equivalentTo:) SpeechTranscriber.installedLocales / supportedLocales when showing language choices. Pick a documented preset: .transcription for basic accurate transcription. .progressiveTranscription for live UI updates. .timeIndexedProgressiveTranscription when playback highlighting needs audioTimeRange . Install required assets with AssetInventory.assetInstallationRequest . Convert live audio buffers to SpeechAnalyzer.bestAvailableAudioFormat(compatibleWith:) before yielding AnalyzerInput . Consume module results from their AsyncSequence in a separate task. Finish explicitly with finalizeAndFinish(through:) , finalizeAndFinishThroughEndOfInput() , or cancelAndFinishNow() . Do not use an offlineTranscription preset; Apple does not document one. Finishing an AsyncStream input sequence does not finish the analyzer session. SFSpeechRecognizer Setup Creating a recognizer with locale import Speech // Default locale (user's current language) let recognizer = SFSpeechRecognizer () // Specific locale let recognizer = SFSpeechRecognizer (locale: Locale (identifier: "en-US" )) // Check if recognition is available for this locale guard let recognizer, recognizer.isAvailable else { print ( "Speech recognition not available" ) return } Monitoring availability changes final class SpeechManager : NSObject , SFSpeechRecognizerDelegate { private let recognizer = SFSpeechRecognizer () ! override init () { super . init () recognizer.delegate = self } func speechRecognizer ( _ speechRecognizer : SFSpeechRecognizer , availabilityDidChange available : Bool ) { // Update UI — disable record button when unavailable } } Authorization Request both speech recognition and microphone permissions before starting live transcription. Add these keys to Info.plist : NSSpeechRecognitionUsageDescription NSMicrophoneUsageDescription import Speech import AVFoundation func requestPermissions () async -> Bool { let speechStatus = await withCheckedContinuation { continuation in SFSpeechRecognizer .requestAuthorization { status in continuation.resume(returning: status) } } guard speechStatus == .authorized else { return false } let micStatus: Bool if #available ( iOS 17 , * ) { micStatus = await AVAudioApplication .requestRecordPermission() } else { micStatus = await withCheckedContinuation { continuation in AVAudioSession .sharedInstance().requestRecordPermission { granted in continuation.resume(returning: granted) } } } return micStatus } Live Microphone Transcription The standard pattern: AVAudioEngine captures microphone audio → buffers are appended to SFSpeechAudioBufferRecognitionRequest → results stream in. import Speech import AVFoundation final class LiveTranscriber { private let recognizer = SFSpeechRecognizer (locale: Locale (identifier: "en-US" )) ! private let audioEngine = AVAudioEngine () private var recognitionRequest: SFSpeechAudioBufferRecognitionRequest ? private var recognitionTask: SFSpeechRecognitionTask ? func startTranscribing () throws { // Cancel any in-progress task recognitionTask ? .cancel() recognitionTask = nil // Configure audio session let audioSession = AVAudioSession .sharedInstance() try audioSession.setCategory(.record, mode: .measurement, options: .duckOthers) try audioSession.setActive( true , options: .notifyOthersOnDeactivation) // Create request let request = SFSpeechAudioBufferRecognitionRequest () request.shouldReportPartialResults = true self .recognitionRequest = request // Start recognition task recognitionTask = recognizer.recognitionTask(with: request) { result, error in if let result { let text = result.bestTranscription.formattedString print ( "Transcription: \(text) " ) if result.isFinal { self .stopTranscribing() } } if let error { print ( "Recognition error: \(error) " ) self .stopTranscribing() } } // Install audio tap let inputNode = audioEngine.inputNode let recordingFormat = inputNode.outputFormat(forBus: 0 ) inputNode.installTap(onBus: 0 , bufferSize: 1024 , format: recordingFormat) { buffer, _ in request.append(buffer) } audioEngine.prepare() try audioEngine.start() } func stopTranscribing () { audioEngine.stop() audioEngine.inputNode.removeTap(onBus: 0 ) recognitionRequest ? .endAudio() recognitionRequest = nil recognitionTask ? .cancel() recognitionTask = nil } } Pre-Recorded Audio File Recognition Use SFSpeechURLRecognitionRequest for audio files on disk: func transcribeFile ( at url : URL ) async throws -> String { guard let recognizer = SFSpeechRecognizer (), recognizer.isAvailable else { throw SpeechError .unavailable } let request = SFSpeechURLRecognitionRequest (url: url) request.shouldReportPartialResults = false return try await withCheckedThrowingContinuation { continuation in var didResume = false recognizer.recognitionTask(with: request) { result, error in guard ! didResume else { return } if let error { didResume = true continuation.resume(throwing: error) } else if let result, result.isFinal { didResume = true continuation.resume( returning: result.bestTranscription.formattedString ) } } } } On-Device vs Server Recognition SFSpeechRecognizer can use on-device recognition for supported locales on iOS 13+. If supportsOnDeviceRecognition is false, the recognizer requires a network connection. requiresOnDeviceRecognition only has effect when the recognizer supports it. let recognizer = SFSpeechRecognizer (locale: Locale (identifier: "en-US" )) ! // Check if on-device is supported for this locale if recognizer.supportsOnDeviceRecognition { let request = SFSpeechAudioBufferRecognitionRequest () request.requiresOnDeviceRecognition = true // Force on-device } SFSpeechRecognizer requests may still be a poor fit for long-form capture. Apple documents a roughly one-minute task limit for speech recognition and other service limits. For long recordings on iOS 26+, prefer SpeechAnalyzer ; otherwise chunk or restart recognition before the limit and preserve transcript state across tasks. Handling Results Partial vs final results With shouldReportPartialResults , replace the displayed partial transcript until SFSpeechRecognitionResult.isFinal commits it. This is separate from SpeechTranscriber.Result.isFinal , whose volatile attributed range must be replaced by the final result for that range. The live example and references/speechanalyzer-patterns.md contain the canonical loops. Accessing alternative transcriptions and confidence recognizer.recognitionTask(with: request) { result, error in guard let result else { return } // Best transcription let best = result.bestTranscription // All alternatives (sorted by confidence, descending) for transcription in result.transcriptions { for segment in transcription.segments { print ( " \(segment.substring) : \(segment.confidence) " ) } } } Adding punctuation (iOS 16+) let request = SFSpeechAudioBufferRecognitionRequest () request.addsPunctuation = true Contextual strings Improve recognition of domain-specific terms: let request = SFSpeechAudioBufferRecognitionRequest () request.contextualStrings = [ "SwiftUI" , "Xcode" , "CloudKit" ] Common Mistakes Mistake Fix Live audio requests only speech authorization Require both speech and microphone permission. Recognizer availability is checked once Observe delegate availability changes and model loss of service. Final/error/rollover paths perform different cleanup Use one stopTranscribing() owner for engine stop, tap removal, endAudio , and task cancellation. On-device mode is forced for every locale Check supportsOnDeviceRecognition and provide a fallback. One SFSpeechRecognizer task is used for long-form capture Prefer SpeechAnalyzer on iOS 26+ or roll bounded segments while preserving committed transcript. Finishing analyzer input is treated as session completion Explicitly finalize through the last sample or cancel-and-finish. Volatile SpeechAnalyzer results are appended Replace the volatile range until a final result commits it. A second recognition task starts before the first ends Cancel/finish the active task and complete cleanup before replacement. Load references/speechanalyzer-patterns.md for complete analyzer finalization and volatile-result code. Review Checklist NSSpeechRecognitionUsageDescription is in Info.plist NSMicrophoneUsageDescription is in Info.plist (if using live audio) Authorization is requested before starting recognition SFSpeechRecognizerDelegate is set to handle availabilityDidChange Audio engine is stopped and tap removed when recognition ends recognitionRequest.endAudio() is called when done recording Previous recognitionTask is canceled before starting a new one supportsOnDeviceRecognition is checked before requiring on-device mode Partial results are handled separately from final ( isFinal ) results SFSpeechRecognizer one-minute/service limits are accounted for For iOS 26+: AssetInventory assets are installed before using SpeechAnalyzer For iOS 26+: SpeechTranscriber.isAvailable and locale support are checked For iOS 26+: live buffers are converted to the analyzer-compatible format For iOS 26+: analyzer sessions are explicitly finalized or canceled For iOS 26+: volatile results are replaced by finalized results, not duplicated References Speech framework SpeechAnalyzer SpeechTranscriber SpeechTranscriber.Preset DictationTranscriber SpeechDetector SFSpeechRecognizer SFSpeechAudioBufferRecognitionRequest SFSpeechURLRecognitionRequest SFSpeechRecognitionResult SFSpeechRecognitionRequest AssetInventory Asking Permission to Use Speech Recognition Recognizing Speech in Live Audio Bring advanced speech-to-text to your app with SpeechAnalyzer