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Read iOS Swift Barcode

I have a barcode scan working in my application. After detecting the barcode, I stop the capture session to allow barcode processing. However, after processing the barcode, I want the scan controller to stay in place and the next barcode to be scanned. I assumed that the start of a capture session (startRunning ()) will do this, but the image will remain frozen. How to start a capture session again?

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Use this code to stop the session.

self.session.stopRunning()

Use this code to get started.

 self.session.startRunning()

Here is all the code for implementing a barcode scanner ...

 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 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() self.alert(detectionString) break } } } println(detectionString) self.highlightView.frame = highlightViewRect self.view.bringSubviewToFront(self.highlightView) } func alert(Code: String){ let actionSheet:UIAlertController = UIAlertController( title: "Barcode", message: "\(Code)", preferredStyle: UIAlertControllerStyle.Alert) // for alert add .Alert instead of .Action Sheet // start copy let firstAlertAction:UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: { (alertAction: UIAlertAction!) in // action when pressed self.session.startRunning() }) actionSheet.addAction(firstAlertAction) // end copy self.presentViewController(actionSheet, animated: true, completion: nil) } }
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edited the above code for quick 2.0:

 import UIKit import AVFoundation class BarCodeViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate { let session : AVCaptureSession = AVCaptureSession() var previewLayer : AVCaptureVideoPreviewLayer! @IBOutlet weak var highlightView: 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 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 var input: AVCaptureDeviceInput = AVCaptureDeviceInput() do { input = try AVCaptureDeviceInput(device: device) as AVCaptureDeviceInput } catch let myJSONError { print(myJSONError) } // If our input is not nil then add it to the session, otherwise we're kind of done! if input != AVCaptureDeviceInput() { session.addInput(input) } else { // This is fine for a demo, do something real with this in your app. :) print(error) } let output = AVCaptureMetadataOutput() output.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue()) session.addOutput(output) output.metadataObjectTypes = output.availableMetadataObjectTypes previewLayer = AVCaptureVideoPreviewLayer(session: session) 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() self.alert(detectionString) break } } } print(detectionString) self.highlightView.frame = highlightViewRect self.view.bringSubviewToFront(self.highlightView) } func alert(Code: String){ let actionSheet:UIAlertController = UIAlertController(title: "Barcode", message: "\(Code)", preferredStyle: UIAlertControllerStyle.Alert) // for alert add .Alert instead of .Action Sheet // start copy let firstAlertAction:UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: { (alertAction:UIAlertAction!) in // action when pressed self.session.startRunning() }) actionSheet.addAction(firstAlertAction) // end copy self.presentViewController(actionSheet, animated: true, completion: nil) } }
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Quick 3.0 version:

 import UIKit import AVFoundation class BarCodeViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate { let session : AVCaptureSession = AVCaptureSession() var previewLayer : AVCaptureVideoPreviewLayer! @IBOutlet weak var highlightView: 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.green.cgColor self.highlightView.layer.borderWidth = 3 // Add it to our controller view as a subview. self.view.addSubview(self.highlightView) // For the sake of discussion this is the camera let device = AVCaptureDevice.defaultDevice(withMediaType: 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 var input: AVCaptureDeviceInput = AVCaptureDeviceInput() do { input = try AVCaptureDeviceInput(device: device) as AVCaptureDeviceInput } catch let myJSONError { print(myJSONError) } // If our input is not nil then add it to the session, otherwise we're kind of done! if input != AVCaptureDeviceInput() { session.addInput(input) } else { // This is fine for a demo, do something real with this in your app. :) print(error!) } let output = AVCaptureMetadataOutput() output.setMetadataObjectsDelegate(self, queue: DispatchQueue.main) session.addOutput(output) output.metadataObjectTypes = output.availableMetadataObjectTypes previewLayer = AVCaptureVideoPreviewLayer(session: session) 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. @nonobjc func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) { var highlightViewRect = CGRect() 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.transformedMetadataObject(for: metadata as! AVMetadataMachineReadableCodeObject) highlightViewRect = barCodeObject.bounds detectionString = (metadata as! AVMetadataMachineReadableCodeObject).stringValue self.session.stopRunning() self.alert(Code: detectionString) break } } } print(detectionString) self.highlightView.frame = highlightViewRect self.view.bringSubview(toFront: self.highlightView) } func alert(Code: String){ let actionSheet:UIAlertController = UIAlertController(title: "Barcode", message: "\(Code)", preferredStyle: UIAlertControllerStyle.alert) // for alert add .Alert instead of .Action Sheet // start copy let firstAlertAction:UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: { (alertAction:UIAlertAction!) in // action when pressed self.session.startRunning() }) actionSheet.addAction(firstAlertAction) // end copy self.present(actionSheet, animated: true, completion: nil) }

}

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