QRCode Reader Appcoda

//
//  ViewController.swift
//  QRReader
//
//  Created by Burak Akkas on 12/09/15.
//

import UIKit
import AVFoundation

class ViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {

    @IBOutlet weak var messageLabel: UILabel!

    var captureSession : AVCaptureSession?
    var videoPreviewLayer : AVCaptureVideoPreviewLayer?
    var qrCodeFrameView : UIView?

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        // Get an instance of the AVCaptureDevice class to initialize a device object and provide the video
        // as the media type parameter.
        let captureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)

        // Get an instance of the AVCaptureDeviceInput class using the previous device object.
        //error:NSError?
        var input : AnyObject!

        do {
            input = try AVCaptureDeviceInput(device: captureDevice)
        } catch _ {
            print("hata")
        }

        // Initialize the captureSession object.
        captureSession = AVCaptureSession()
        // Set the input device on the capture session.
        captureSession?.addInput(input as! AVCaptureInput)

        // Initialize a AVCaptureMetadataOutput object and set it as the output device to the capture session.
        let captureMetadataOutput = AVCaptureMetadataOutput()
        captureSession?.addOutput(captureMetadataOutput)

        // Set delegate and use the default dispatch queue to execute the call back
        captureMetadataOutput.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
        captureMetadataOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode]

        // Initialize the video preview layer and add it as a sublayer to the viewPreview view's layer.
        videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        videoPreviewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
        videoPreviewLayer?.frame = view.layer.bounds
        view.layer.addSublayer(videoPreviewLayer!)

        captureSession?.startRunning()
        view.bringSubviewToFront(messageLabel)

        // Initialize QR Code Frame to highlight the QR code
        qrCodeFrameView = UIView()
        qrCodeFrameView?.layer.borderColor = UIColor.greenColor().CGColor
        qrCodeFrameView?.layer.borderWidth = 2
        view.addSubview(qrCodeFrameView!)
        view.bringSubviewToFront(qrCodeFrameView!)

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

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

        // Check if the metadataObjects array is not nil and it contains at least one object.
        if metadataObjects == nil || metadataObjects.count == 0 {
            qrCodeFrameView?.frame = CGRectZero
            messageLabel.text = "No QR code is detected"
            return
        }

        // Get the metadata object.
        let metadataObj = metadataObjects[0] as! AVMetadataMachineReadableCodeObject

        if metadataObj.type == AVMetadataObjectTypeQRCode {
            // If the found metadata is equal to the QR code metadata then update the status label's text and set the bounds
            let barCodeObject = videoPreviewLayer?.transformedMetadataObjectForMetadataObject(metadataObj as AVMetadataMachineReadableCodeObject) as! AVMetadataMachineReadableCodeObject
            qrCodeFrameView?.frame = barCodeObject.bounds;

            if metadataObj.stringValue != nil {
                messageLabel.text = metadataObj.stringValue
            }
        }
    }


}