I’m experiencing a crash at runtime when trying to extract audio from a video. This issue occurs on both iOS 18 and earlier versions. The crash is caused by the following error:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '*** -[AVAssetExportSession exportAsynchronouslyWithCompletionHandler:] Cannot call exportAsynchronouslyWithCompletionHandler: more than once.
(0x1851435ec 0x1826dd244 0x1970c09c0 0x214d8f358 0x214d95899 0x190a1c8b9 0x214d8efd9 0x30204cef5 0x302053ab9 0x190a5ae39)
libc++abi: terminating due to uncaught exception of type NSException
My previous code worked fine, but it's crashing with Swift 6.
Does anyone know a solution for this?
Previous code:
func extractAudioFromVideo(from videoURL: URL, exportHandler: ((AVAssetExportSession, CurrentValueSubject<Float, Never>?) -> Void)? = nil, completion: @escaping (Swift.Result<URL, Error>) -> Void) {
let asset = AVAsset(url: videoURL)
// Create an AVAssetExportSession to export the audio track
guard let exportSession = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetAppleM4A) else {
completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Failed to create AVAssetExportSession"])))
return
}
// Set the output file type and path
guard let filename = videoURL.lastPathComponent.components(separatedBy: ["."]).first else { return }
let outputURL = VideoUtils.getTempAudioExportUrl(filename)
VideoUtils.deleteFileIfExists(outputURL.path)
exportSession.outputFileType = .m4a
exportSession.outputURL = outputURL
let audioExportProgressPublisher = CurrentValueSubject<Float, Never>(0.0)
if let exportHandler = exportHandler {
exportHandler(exportSession, audioExportProgressPublisher)
}
// Periodically check the progress of the export session
let timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { _ in
audioExportProgressPublisher.send(exportSession.progress)
}
// Export the audio track asynchronously
exportSession.exportAsynchronously {
switch exportSession.status {
case .completed:
completion(.success(outputURL))
case .failed:
completion(.failure(exportSession.error ?? NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown error occurred while exporting audio"])))
case .cancelled:
completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Export session was cancelled"])))
default:
completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown export session status"])))
}
// Invalidate the timer when the export session completes or is cancelled
timer.invalidate()
}
}
## New Code:
func extractAudioFromVideo(from videoURL: URL, exportHandler: ((AVAssetExportSession, CurrentValueSubject<Float, Never>?) -> Void)? = nil, completion: @escaping (Swift.Result<URL, Error>) -> Void)
{
let asset = AVAsset(url: videoURL)
// Create an AVAssetExportSession to export the audio track
guard let exportSession = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetAppleM4A) else {
completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Failed to create AVAssetExportSession"])))
return
}
// Set the output file type and path
guard let filename = videoURL.lastPathComponent.components(separatedBy: ["."]).first else { return }
let outputURL = VideoUtils.getTempAudioExportUrl(filename)
VideoUtils.deleteFileIfExists(outputURL.path)
exportSession.outputFileType = .m4a
exportSession.outputURL = outputURL
let audioExportProgressPublisher = CurrentValueSubject<Float, Never>(0.0)
if let exportHandler {
exportHandler(exportSession, audioExportProgressPublisher)
}
let task = Task {
if #available(iOS 18.0, *) {
// Handle export for iOS 18 and later
let states = exportSession.states(updateInterval: 0.1)
for await state in states {
switch state {
case .pending, .waiting:
break
case .exporting(progress: let progress):
print("Exporting: \(progress.fractionCompleted)")
if progress.isFinished {
completion(.success(outputURL))
} else if progress.isCancelled {
completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Export session was cancelled"])))
} else {
audioExportProgressPublisher.send(Float(progress.fractionCompleted))
}
}
}
try await exportSession.export(to: outputURL, as: .m4a) // Only call export once
} else {
// Handle export for iOS versions below 18
let publishTimer = Timer.publish(every: 0.1, on: .main, in: .common)
.autoconnect()
.sink { [weak exportSession] _ in
guard let exportSession = exportSession else { return }
audioExportProgressPublisher.send(exportSession.progress)
}
// Only call export once
await exportSession.export()
// Handle the export session's status
switch exportSession.status {
case .completed:
completion(.success(outputURL))
case .failed:
completion(.failure(exportSession.error ?? NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown error occurred while exporting audio"])))
case .cancelled:
completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Export session was cancelled"])))
default:
completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown export session status"])))
}
// Invalidate the timer when the export session completes or is cancelled
publishTimer.cancel()
}
}
task.cancel()
}
