Speech Recognition

Transcribe live and pre-recorded audio to text using Apple's Speech framework. Covers SFSpeechRecognizer (iOS 10+) and the new SpeechAnalyzer API (iOS 26+).

Contents

• SpeechAnalyzer (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 (iOS 26+)

SpeechAnalyzer is an actor-based API introduced in iOS 26 that replaces SFSpeechRecognizer for new projects. It uses Swift concurrency, AsyncSequence for results, and supports modular analysis via SpeechTranscriber.

Basic transcription with SpeechAnalyzer

import Speech

// 1. Create a transcriber module
guard let locale = SpeechTranscriber.supportedLocale(
    equivalentTo: Locale.current
) else { return }
let transcriber = SpeechTranscriber(locale: locale, preset: .offlineTranscription)

// 2. Ensure assets are installed
if let request = try await AssetInventory.assetInstallationRequest(
    supporting: [transcriber]
) {
    try await request.downloadAndInstall()
}

// 3. Create input stream and analyzer
let (inputSequence, inputBuilder) = AsyncStream.makeStream(of: AnalyzerInput.self)
let audioFormat = await SpeechAnalyzer.bestAvailableAudioFormat(
    compatibleWith: [transcriber]
)
let analyzer = SpeechAnalyzer(modules: [transcriber])

// 4. Feed audio buffers (from AVAudioEngine or file)
Task {
    // Append PCM buffers converted to audioFormat
    let pcmBuffer: AVAudioPCMBuffer = // ... your audio buffer
    inputBuilder.yield(AnalyzerInput(buffer: pcmBuffer))
    inputBuilder.finish()
}

// 5. Consume results
Task {
    for try await result in transcriber.results {
        let text = String(result.text.characters)
        print(text)
    }
}

// 6. Run analysis
let lastSampleTime = try await analyzer.analyzeSequence(inputSequence)

// 7. Finalize
if let lastSampleTime {
    try await analyzer.finalizeAndFinish(through: lastSampleTime)
} else {
    try analyzer.cancelAndFinishNow()
}

Transcribing an audio file with SpeechAnalyzer

let transcriber = SpeechTranscriber(locale: locale, preset: .offlineTranscription)
let audioFile = try AVAudioFile(forReading: fileURL)
let analyzer = SpeechAnalyzer(
    inputAudioFile: audioFile, modules: [transcriber], finishAfterFile: true
)
for try await result in transcriber.results {
    print(String(result.text.characters))
}

Key differences from SFSpeechRecognizer

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