How Can I Record Karoke while Headphone is plug-in?

Question

I want to make a karaoke app and everything is perfect, without headphone plug-in. [.MixWithOthers, .DefaultToSpeaker])

I want to set it to [.MixWithOthers, .DefaultToHeadPhones])

but there is not any function like that. However mix recording not working when headphone plugged-in. It's my sample code: https://github.com/genedelisa/AVFoundationRecorder/blob/master/AVFoundation%20Recorder/RecorderViewController.swift

func setSessionPlayback() { let session:AVAudioSession = AVAudioSession.sharedInstance()

    do {
        try session.setCategory(AVAudioSessionCategoryPlayAndRecord)
    } catch let error as NSError {
        print("could not set session category")
        print(error.localizedDescription)
    }
    do {
       // try session.setActive(true)
    } catch let error as NSError {
        print("could not make session active")
        print(error.localizedDescription)
    }
}

func setSessionPlayAndRecord()
{
    let session = AVAudioSession.sharedInstance()
    do {

      //  var setCategoryErr: NSError? = nil
      //  var activationErr: NSError? = nil
        //Set the general audio session category
        try session.setCategory(AVAudioSessionCategoryPlayAndRecord)
        var doChangeDefaultRoute: UInt32 = 1
        do {
            try session.setCategory(AVAudioSessionCategoryPlayAndRecord,
                                    withOptions:AVAudioSessionCategoryOptions.DefaultToSpeaker)
        }
        catch let error {

        }

        //Activate the customized audio session
         try session.setActive(true)

    } catch let error as NSError {
        print("could not set session category")
        print(error.localizedDescription)
    }
    do {
       // try session.setActive(true)
    } catch let error as NSError {
        print("could not make session active")
        print(error.localizedDescription)
    }
}