Simple Barcode Scanning with Swift

ViewController.swift

import UIKit
import AVFoundation


class ViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {

    let session         : AVCaptureSession = AVCaptureSession()
    var previewLayer    : AVCaptureVideoPreviewLayer!
    var highlightView   : UIView = UIView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Allow the view to resize freely
        self.highlightView.autoresizingMask =   UIViewAutoresizing.FlexibleTopMargin |
                                                UIViewAutoresizing.FlexibleBottomMargin |
                                                UIViewAutoresizing.FlexibleLeftMargin |
                                                UIViewAutoresizing.FlexibleRightMargin
        
        // Select the color you want for the completed scan reticle
        self.highlightView.layer.borderColor = UIColor.greenColor().CGColor
        self.highlightView.layer.borderWidth = 3
        
        // Add it to our controller's view as a subview.
        self.view.addSubview(self.highlightView)
     
        
        // For the sake of discussion this is the camera
        let device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
        
        // Create a nilable NSError to hand off to the next method.
        // Make sure to use the "var" keyword and not "let"
        var error : NSError? = nil
        
        
        let input : AVCaptureDeviceInput? = AVCaptureDeviceInput.deviceInputWithDevice(device, error: &error) as? AVCaptureDeviceInput
        
        // If our input is not nil then add it to the session, otherwise we're kind of done!
        if input != nil {
            session.addInput(input)
        }
        else {
            // This is fine for a demo, do something real with this in your app. :)
            println(error)
        }
        
        let output = AVCaptureMetadataOutput()
        output.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
        session.addOutput(output)
        output.metadataObjectTypes = output.availableMetadataObjectTypes
        
        
        previewLayer = AVCaptureVideoPreviewLayer.layerWithSession(session) as AVCaptureVideoPreviewLayer
        previewLayer.frame = self.view.bounds
        previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
        self.view.layer.addSublayer(previewLayer)
        
        // Start the scanner. You'll have to end it yourself later.
        session.startRunning()

    }
    
    // This is called when we find a known barcode type with the camera.
    func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
        
        var highlightViewRect = CGRectZero
        
        var barCodeObject : AVMetadataObject!
        
        var detectionString : String!
        
        let barCodeTypes = [AVMetadataObjectTypeUPCECode,
            AVMetadataObjectTypeCode39Code,
            AVMetadataObjectTypeCode39Mod43Code,
            AVMetadataObjectTypeEAN13Code,
            AVMetadataObjectTypeEAN8Code,
            AVMetadataObjectTypeCode93Code,
            AVMetadataObjectTypeCode128Code,
            AVMetadataObjectTypePDF417Code,
            AVMetadataObjectTypeQRCode,
            AVMetadataObjectTypeAztecCode
        ]
        
        
        // The scanner is capable of capturing multiple 2-dimensional barcodes in one scan.
        for metadata in metadataObjects {
            
            for barcodeType in barCodeTypes {
                
                if metadata.type == barcodeType {
                    barCodeObject = self.previewLayer.transformedMetadataObjectForMetadataObject(metadata as AVMetadataMachineReadableCodeObject)
                    
                    highlightViewRect = barCodeObject.bounds
                    
                    detectionString = (metadata as AVMetadataMachineReadableCodeObject).stringValue
                    
                    self.session.stopRunning()
                    break
                }
                
            }
        }
        
        println(detectionString)
        self.highlightView.frame = highlightViewRect
        self.view.bringSubviewToFront(self.highlightView)

    }


}