Scanning the barcode

ScannerViewController.swift

import AVFoundation
import UIKit
    
class ScannerViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
        var captureSession: AVCaptureSession!
        var previewLayer: AVCaptureVideoPreviewLayer!
        
        override func viewDidLoad() {
            super.viewDidLoad()
            self.navigationItem.title = "Scanner"
            let cancelButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Cancel, target: self, action: #selector(ScannerViewController.cancelAction(_:)))
            self.navigationItem.leftBarButtonItem = cancelButton
            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,AVMetadataObjectTypeInterleaved2of5Code,AVMetadataObjectTypeCode128Code,AVMetadataObjectTypeCode39Code]
            } else {
                failed()
                return
            }
            
            previewLayer = AVCaptureVideoPreviewLayer(session: captureSession);
            previewLayer.frame = CGRectMake(0, ScreenConstant.height/2, ScreenConstant.width, 100);
            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)
    }
    func cancelAction(sender:AnyObject){
       self.dismissViewControllerAnimated(true, completion: nil)
    }
        
    override func prefersStatusBarHidden() -> Bool {
            return true
    }
        
    override func supportedInterfaceOrientations() -> UIInterfaceOrientationMask {
            return .Portrait
        }
    }