AVAssetWriter can not call the method startWriting - ios

Question

Thanks for everyone.
This is my set AVAssetWriter code.
And Error is
Error Domain=AVFoundationErrorDomain Code=-11800 " """ UserInfo={NSLocalizedFailureReason=""（-12780）, NSLocalizedDescription="", NSUnderlyingError=0x1c465a310 {Error Domain=NSOSStatusErrorDomain Code=-12780 "(null)"}}
private func createWriter(assetURL: URL) {
guard let assetWriter = try? AVAssetWriter.init(url: assetURL, fileType: AVFileType.mov) else { return }
...
videoWriterInput = AVAssetWriterInput.init(mediaType: AVMediaType.video, outputSettings: outputSettings)
videoWriterInput?.expectsMediaDataInRealTime = true
videoWriterInput?.transform = videoWriterInput!.transform.rotated(by: CGFloat.pi / 2)
audioWriterInput = AVAssetWriterInput.init(mediaType: AVMediaType.audio, outputSettings: nil)
audioWriterInput?.expectsMediaDataInRealTime = true
let SPBADictionary: [String: Any] = [kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA,
kCVPixelBufferWidthKey as String: kScreenWidth,
kCVPixelBufferHeightKey as String:kScreenHeight,
kCVPixelFormatOpenGLESCompatibility as String: kCFBooleanTrue]
assetWriterPixelBufferInput = AVAssetWriterInputPixelBufferAdaptor.init(assetWriterInput: videoWriterInput!, sourcePixelBufferAttributes: SPBADictionary)
assetWriter.shouldOptimizeForNetworkUse = true
if assetWriter.canAdd(videoWriterInput!) {
assetWriter.add(videoWriterInput!)
}
if assetWriter.canAdd(audioWriterInput!) {
assetWriter.add(audioWriterInput!)
}
}
And this is the callback code, I do not know why startWriting is not use, the AVAssetWriterStatus can not be writing, so it will crash and give me error -11800, unknown error.
func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
if !isRecoding { return }
guard let assetWriter = assetWriter else { return }
autoreleasepool {
let currentSampleTime = CMSampleBufferGetOutputPresentationTimeStamp(sampleBuffer)
if assetWriter.status != .writing {
assetWriter.startWriting()
assetWriter.startSession(atSourceTime: currentSampleTime)
}
if assetWriter.status != .writing{
print("Warning: writer status is \(assetWriter.status.rawValue)")
if assetWriter.status == AVAssetWriterStatus.failed {
print(assetWriter.error ?? "")
return
}
}
if output == videoOutput {
if let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer),videoWriterInput?.isReadyForMoreMediaData ?? false {
print("videoWriterInput")
assetWriterPixelBufferInput?.append(pixelBuffer, withPresentationTime: currentSampleTime)
}
}
if output == audioOutput {
if audioWriterInput?.isReadyForMoreMediaData ?? false {
print("audioWriterInput")
audioWriterInput?.append(sampleBuffer)
}
}
}
}

Answer 1

One of the reasons that causes "startWriting()" to fail, is that the given URL is invalid. I'd suggest you to take a look at:
The file specified in the URL does NOT exist. (Confirm that with
FileManager.fileExists(atPath:).)
All directories to that URL have
been created. (Explicitely create them with FileManager.createDirectory(at:withIntermediateDirectories:attributes:).)