How to access Mac default camera using swift xcode

Today i am coding for Mac first time. What I am trying to do is access the default camera and show a preview. 2nd step i will record or take a snap if i need. For the 1st step i have written the following code

import Cocoa
import AVFoundation
class ViewController: NSViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        var session:AVCaptureSession = AVCaptureSession()
        session.sessionPreset = AVCaptureSessionPresetLow
        var device:AVCaptureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
        //Preview
        var previewLayer:AVCaptureVideoPreviewLayer = AVCaptureVideoPreviewLayer(session: session)
        var myView:NSView = self.view
        previewLayer.frame = myView.bounds
        previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
        self.view.layer?.addSublayer(previewLayer)
        session.startRunning()
    }
    override var representedObject: AnyObject? {
        didSet {
        // Update the view, if already loaded.
        }
    }
}

I don't see this code is turning on my laptop default camera or displaying anything on the view. What am i doing wrong here? Any direction or any example i can look for even if its in Obj-C would be really helpful. TIA.

In your code the

self.view.layer?.addSublayer(previewLayer)

will not be executed since self.view.layer is nil so that won't be executed.

Alas, this does not seem to be only issue since even when adding a layer the camera does not start working. You will likely have to dig into this:

https://developer.apple.com/library/mac/samplecode/AVRecorder/Introduction/Intro.html