Audio URL cannot be played even though the file exists and is reachable

Question

I have written a download function in my app which downloads a .mp3 file from a url and saves it into Application Support directory locally.

func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
     if let url = downloadTask.originalRequest?.url {
            let destinationURL = moveFileToSupportDirectory(source: location, fileName: url.lastPathComponent , subDir: "MyApp")
            onDownloadComplete?(destinationURL, nil)
     }
}

func moveFileToSupportDirectory(source: URL, fileName: String, subDir: String) -> URL? {
    do {
        let manager = FileManager.default
        let directoryURL = try manager.url(for: .applicationSupportDirectory, in: .userDomainMask, appropriateFor: nil, create: true).appendingPathComponent(subDir)
        let destination = directoryURL.appendingPathComponent(fileName)
        do {
            try FileManager.default.createDirectory (at: directoryURL, withIntermediateDirectories: true, attributes: nil)
        } catch {
            print("Error creating directory: \(error)")
            return nil
        }
        if FileManager().fileExists(atPath: destination.path) {
            print("File already exists [\(destination.path)]")
            return destination
        }
        else {
            print("Move from \(source.path) to destination \(destination.path)...")
            try manager.moveItem(at: source, to: destination)
            return destination
        }
    } catch {
        printTrace("\(error)")
        return nil
    }
}

After that when user presses "Play" button, the app will retrieve the saved URL using fileName and play it locally.

The function of retrieving URL:

func getSavedURL(of name: String) -> URL? {
    do {
        let manager = FileManager.default
        let directoryURL = try manager.url(for: .applicationSupportDirectory, in: .userDomainMask, appropriateFor: nil, create: true).appendingPathComponent("MyApp")
        let destination = directoryURL.appendingPathComponent(name)
        if FileManager().fileExists(atPath: destination.path) {
            print("File exists [\(destination.path)]")
            let isReachable = try destination.checkResourceIsReachable()
            if isReachable {
                print("File is reachable \(destination.absoluteString)")
                return destination
            } else {
                print("File is unreachable")
                return nil
            }
        }
        else {
            print("File \(name) doesn't exist")
            return nil
        }
    } catch {
        print("\(error)")
        return nil
    }
}

The question is that when I download and play it in the same build, all works perfectly. However if I start another build and play the file saved previously, the audio player will throw following error:

ExtAudioFile.cpp:193:Open: about to throw 'wht?': open audio file
[avae]            AVAEInternal.h:109   [AVAudioFile.mm:134:AVAudioFileImpl: (ExtAudioFileOpenURL((CFURLRef)fileURL, &_extAudioFile)): error 2003334207

From this thread the error seems to be related to nil of audio file:
OSStatus error 2003334207 when using AVAudioPlayer

But when retrieving the URL it has already passed all the checks (i.e. exists and is reachable) and return a non-nil URL. How come the audio file cannot be played properly even though it does exist and is reachable?

Is it related to this sandbox issue?
Document directory path change when rebuild application.
But I retrieve the URL using the relative method, I think this should not happen in my case.

p.s. I use SwiftAudioPlayer to play my audio file locally. It seems to use AudioEngine inside.