Swift Barcode Scanner

controller.swift

//
//  SecondViewController.swift
//  Scanmaster
//
//  Created by Matthias Schmidt on 05/01/2017.
//  Copyright © 2017 Pixelflush. All rights reserved.
//

import UIKit
import AVFoundation

class SecondViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {

    var session: AVCaptureSession!
    var previewLayer: AVCaptureVideoPreviewLayer!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        print("test 1")
        
        // Create a session object.
        session = AVCaptureSession()
        
        // Set the captureDevice.
        let videoCaptureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
        
        // Create input object.
        let videoInput: AVCaptureDeviceInput?
        
        do {
            videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice)
        } catch {
            print("return")
            return
        }
        
        // Add input to the session.
        if (session.canAddInput(videoInput)) {
            session.addInput(videoInput)
        } else {
            scanningNotPossible()
        }
        
        let metadataOutput = AVCaptureMetadataOutput()
        
        // Add output to the session.
        if (session.canAddOutput(metadataOutput)) {
            session.addOutput(metadataOutput)
            
            // Send captured data to the delegate object via a serial queue.
            metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
            
            // Set barcode type for which to scan: Code128.
            metadataOutput.metadataObjectTypes = [AVMetadataObjectTypeCode128Code]
            
            // Add previewLayer and have it show the video data.
            previewLayer = AVCaptureVideoPreviewLayer(session: session);
            previewLayer.frame = view.layer.bounds;
            previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
            view.layer.addSublayer(previewLayer);
            
            // Begin the capture session.
            
            session.startRunning()
        } else {
            scanningNotPossible()
        }
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    func scanningNotPossible() {
        print("scanningNotPossible()")
        // Let the user know that scanning isn't possible with the current device.
        let alert = UIAlertController(title: "Can't Scan.", message: "Let's try a device equipped with a camera.", preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
        present(alert, animated: true, completion: nil)
        session = nil
    }
    
    func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
        // Get the first object from the metadataObjects array.
        if let barcodeData = metadataObjects.first {
            // Turn it into machine readable code
            let barcodeReadable = barcodeData as? AVMetadataMachineReadableCodeObject;
            if let readableCode = barcodeReadable {
                // Send the barcode as a string to barcodeDetected()
//                barcodeDetected(readableCode.stringValue);
                print(readableCode.stringValue)
            }
            
            // Vibrate the device to give the user some feedback.
            AudioServicesPlaySystemSound(SystemSoundID(kSystemSoundID_Vibrate))
            
            // Avoid a very buzzy device.
            session.stopRunning()
        }
    }
}