Quellcode
- import UIKit
- import AVFoundation
- class QRScannerController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
- var scannedID: Int32 = -1
- var cfgItmdict = NSDictionary()
- var captureSession:AVCaptureSession?
- var videoPreviewLayer:AVCaptureVideoPreviewLayer?
- var qrCodeFrameView:UIView?
- let supportedCodeTypes = [AVMetadataObjectTypeUPCECode,
- AVMetadataObjectTypeCode39Code,
- AVMetadataObjectTypeCode39Mod43Code,
- AVMetadataObjectTypeCode93Code,
- AVMetadataObjectTypeCode128Code,
- AVMetadataObjectTypeEAN8Code,
- AVMetadataObjectTypeEAN13Code,
- AVMetadataObjectTypeAztecCode,
- AVMetadataObjectTypePDF417Code,
- AVMetadataObjectTypeQRCode]
- @IBOutlet weak var topbar: UIView!
- @IBOutlet weak var messageLable: UILabel!
- override func viewDidLoad() {
- super.viewDidLoad()
- qrcodescan()
- // Do any additional setup after loading the view.
- }
- override func didReceiveMemoryWarning() {
- super.didReceiveMemoryWarning()
- // Dispose of any resources that can be recreated.
- }
- @IBAction func exitScan(_ sender: Any) {
- dismiss(animated: true, completion: nil)
- }
- func qrcodescan() {
- let captureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
- do {
- // Get an instance of the AVCaptureDeviceInput class using the previous device object.
- let input = try AVCaptureDeviceInput(device: captureDevice)
- // Initialize the captureSession object.
- captureSession = AVCaptureSession()
- // Set the input device on the capture session.
- captureSession?.addInput(input)
- // 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: DispatchQueue.main)
- captureMetadataOutput.metadataObjectTypes = supportedCodeTypes
- // 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!)
- // Start video capture.
- captureSession?.startRunning()
- // Move the message label and top bar to the front
- view.bringSubview(toFront: messageLable)
- view.bringSubview(toFront: topbar)
- // Initialize QR Code Frame to highlight the QR code
- qrCodeFrameView = UIView()
- if let qrCodeFrameView = qrCodeFrameView {
- qrCodeFrameView.layer.borderColor = UIColor.green.cgColor
- qrCodeFrameView.layer.borderWidth = 2
- view.addSubview(qrCodeFrameView)
- view.bringSubview(toFront: qrCodeFrameView)
- }
- } catch {
- // If any error occurs, simply print it out and don't continue any more.
- print(error)
- return
- }
- }
- func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from 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 = CGRect.zero
- messageLable.text = "No QR/barcode is detected"
- return
- }
- // Get the metadata object.
- let metadataObj = metadataObjects[0] as! AVMetadataMachineReadableCodeObject
- if supportedCodeTypes.contains(metadataObj.type) {
- // 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?.transformedMetadataObject(for: metadataObj)
- qrCodeFrameView?.frame = barCodeObject!.bounds
- if metadataObj.stringValue != nil {
- messageLable.text = metadataObj.stringValue
- scannedID = Int32(metadataObj.stringValue)!
- performSegue(withIdentifier: "segueBackHome", sender: self)
- }
- }
- }
- override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
- if segue.identifier == "segueBackHome" {
- let homeViewController = segue.destination as! HomeViewController
- homeViewController.scanID = scannedID
- }
- }
- /*
- // MARK: - Navigation
- // In a storyboard-based application, you will often want to do a little preparation before navigation
- override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
- // Get the new view controller using segue.destinationViewController.
- // Pass the selected object to the new view controller.
- }
- */
- }
ich habe in meine App einen QRCode Scanner eingebaut, nach einem Tutorial das ich im Internet gefunden habe. Der Scanner an sich funktioniert super. Nach erkennen eines Codes soll ein Segue ausführt werden, mit dem dann der gescannte Wert zurück übergeben wird. Es ist allerdings so, das dieses Segue 2mal ausgeführt wird so das ich in einem Navigationcontroller-Foo lande.
Es geht um diese Stelle:
if metadataObj.stringValue != nil {
messageLable.text = metadataObj.stringValue
scannedID = Int32(metadataObj.stringValue)!
performSegue(withIdentifier: "segueBackHome", sender: self)
Wie kann ich verhindern, das dieses segue 2 mal ausgeführt wird?.
Danke
Dirk