ScannerViewController.swift

import AVFoundation
import UIKit

class ScannerViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
	var captureSession: AVCaptureSession!
	var previewLayer: AVCaptureVideoPreviewLayer!

	override func viewDidLoad() {
		super.viewDidLoad()

		view.backgroundColor = UIColor.blackColor()
		captureSession = AVCaptureSession()

		let videoCaptureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
		let videoInput: AVCaptureDeviceInput

		do {
			videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice)
		} catch {
			return
		}

		if (captureSession.canAddInput(videoInput)) {
			captureSession.addInput(videoInput)
		} else {
			failed();
			return;
		}

		let metadataOutput = AVCaptureMetadataOutput()

		if (captureSession.canAddOutput(metadataOutput)) {
			captureSession.addOutput(metadataOutput)

			metadataOutput.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
			metadataOutput.metadataObjectTypes = [AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypePDF417Code]
		} else {
			failed()
			return
		}

		previewLayer = AVCaptureVideoPreviewLayer(session: captureSession);
		previewLayer.frame = view.layer.bounds;
		previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
		view.layer.addSublayer(previewLayer);

		captureSession.startRunning();
	}

	func failed() {
		let ac = UIAlertController(title: "Scanning not supported", message: "Your device does not support scanning a code from an item. Please use a device with a camera.", preferredStyle: .Alert)
		ac.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
		presentViewController(ac, animated: true, completion: nil)
		captureSession = nil
	}

	override func viewWillAppear(animated: Bool) {
		super.viewWillAppear(animated)

		if (captureSession?.running == false) {
			captureSession.startRunning();
		}
	}

	override func viewWillDisappear(animated: Bool) {
		super.viewWillDisappear(animated)

		if (captureSession?.running == true) {
			captureSession.stopRunning();
		}
	}

	func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
		captureSession.stopRunning()

		if let metadataObject = metadataObjects.first {
			let readableObject = metadataObject as! AVMetadataMachineReadableCodeObject;

			AudioServicesPlaySystemSound(SystemSoundID(kSystemSoundID_Vibrate))
			foundCode(readableObject.stringValue);
		}

		dismissViewControllerAnimated(true, completion: nil)
	}

	func foundCode(code: String) {
		print(code)
	}

	override func prefersStatusBarHidden() -> Bool {
		return true
	}

	override func supportedInterfaceOrientations() -> UIInterfaceOrientationMask {
		return .Portrait
	}
}