How to record audio with AVAudioEngine with seek position to overwrite the sound?

Question

Apple's Memos Recorder app can overwrite previously recorded audio. During your recording, you can PAUSE and move back on audio and record on it again. I want to clone this feature.

I create an AVAudioEngine and install a TAP on the output of mainMixer and write the PCMBuffer down to a file. I can save file in different linear PCM Formats. The problem is when I want to set AudioFile.framePosition it calls the EXTAudioFileSeek() function. This function as Apple's documentation mentioned: "This function’s behavior with files open for writing is undefined.". I then get follwoing error:

EXCEPTION (-66568): "seek to frame in audio file"

It means I can not use this function to seek the position on AudioFile that created for writing. (I accept it)

I want to know do we have another function in Core Audio that help me to write from a position on a AudioFile?

I follow @RomanTsopin structure and it works properly.

var engine = AVAudioEngine()
var file: AVAudioFile?
var player = AVAudioPlayerNode() // if you need play record later

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    file = AVAudioFile(forWriting: URLFor("my_file.caf")!, settings: engine.inputNode.inputFormatForBus(0).settings, error: nil)
    engine.attachNode(player)
    engine.connect(player, to: engine.mainMixerNode, format: engine.mainMixerNode.outputFormatForBus(0)) //configure graph
    engine.startAndReturnError(nil)
}

@IBAction func record(sender: AnyObject) {
    engine.inputNode.installTapOnBus(0, bufferSize: 1024, format: engine.mainMixerNode.outputFormatForBus(0)) { (buffer, time) -> Void in
        self.file?.writeFromBuffer(buffer, error: nil)
        return
    }
}

@IBAction func stop(sender: AnyObject) {
    engine.inputNode.removeTapOnBus(0)
}


func URLFor(filename: String) -> NSURL? {
    if let dirs : [String] = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.AllDomainsMask, true) as? [String] {
        let dir = dirs[0] //documents directory
        let path = dir.stringByAppendingPathComponent(filename)
        return NSURL(fileURLWithPath: path)
    }
    return nil
}

After pause the recording, I want to change the position of writing pointer and write from that position into file.

I am going to try AudioFileWritePackets because it gets inStartingPacket (The packet index for the placement of the first provided packet.)

What do you think? Any idea can help, thanks.