My View disappear when i scan a QR code - ios

Question

i am using the AVFoundation for the first time, and i have gotten my script working kinda...
I am making a ticket app, witch are scanning a QR code on the tickets and checks the database if its used. (I have hidden my API logins). But as soon as i scans the qr code, my code runs, i get a ticket Valid plottet in the console, but the the viewcontroller dissmisses, and goes back to my login page.
I am using this code, for my login page to show the viewcontroller with the QR code.
let viewController:UIViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "scanner") as UIViewController
self.present(viewController, animated: false, completion: nil)
And the the viewcontroller with the QR Scanner.
//
// scanner.swift
// GB Billet Scanner
//
// Created by Benjamin Eibye on 26/12/2017.
// Copyright © 2017 GymBilletter.dk. All rights reserved.
//
import UIKit
import AVFoundation
import Alamofire
class scanner: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
#IBOutlet weak var videoPreview: UIView!
#IBOutlet weak var navnLabel: UILabel!
let avCaptureSession = AVCaptureSession()
var returnValue: String = String()
enum error: Error {
case noCameraAvailable
case videoInputInitFail
}
override func viewDidLoad() {
super.viewDidLoad()
// Creating session
do {
try scanQRCode()
} catch {
print("Failed to scan the QR/BarCode")
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
avCaptureSession.stopRunning()
if let metadataObject = metadataObjects.first {
let readableObject = metadataObject as! AVMetadataMachineReadableCodeObject;
AudioServicesPlaySystemSound(SystemSoundID(kSystemSoundID_Vibrate))
//print(readableObject.stringValue!);
navnLabel.text = "Indlæser billet #\(readableObject.stringValue!)"
let urlEnc = "https://domain?token=\(String(describing: UserDefaults.standard.object(forKey: "token")!))&ticket=\(readableObject.stringValue!)"
Alamofire.request(urlEnc).responseJSON { response in
//print(urlEnc)
//debugPrint(response)
//print(response.result)
if let result = response.result.value {
let JSON = result as! NSDictionary
if JSON["error"] as? Int == 5002 {
print("User not Authendicated")
print(urlEnc)
self.navnLabel.text = "Telefonen er ikke logget ind"
self.avCaptureSession.startRunning()
} else if JSON["error"] as? Int == 5003 {
print("Ticket not Found")
self.navnLabel.text = "Billetten blev ikke fundet"
self.avCaptureSession.startRunning()
} else {
// Billetten eksistere
print("Billet fundet")
if JSON["active"] as! String == "1" {
print("ticket Valid")
self.avCaptureSession.startRunning()
} else {
print("Billetten er blevet brugt")
self.navnLabel.text = "Billetten er blevet brugt \(String(describing: JSON["used_date"]))"
}
}
}
}
}
dismiss(animated: true)
}
func scanQRCode() throws {
guard let avCaptureDevice = AVCaptureDevice.default(for: AVMediaType.video) else {
print("no camera.")
throw error.noCameraAvailable
}
guard let avCaptureInput = try? AVCaptureDeviceInput(device: avCaptureDevice) else {
print("Faild to init camera.")
throw error.videoInputInitFail
}
let avCaptureMetadataOutput = AVCaptureMetadataOutput()
avCaptureMetadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
avCaptureSession.addInput(avCaptureInput)
avCaptureSession.addOutput(avCaptureMetadataOutput)
avCaptureMetadataOutput.metadataObjectTypes = [AVMetadataObject.ObjectType.qr]
let avCaptureVideoPreviewLayer = AVCaptureVideoPreviewLayer(session: avCaptureSession)
avCaptureVideoPreviewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill
avCaptureVideoPreviewLayer.frame = videoPreview.bounds
self.videoPreview.layer.addSublayer(avCaptureVideoPreviewLayer)
avCaptureSession.startRunning()
}
#IBAction func anuller(_ sender: Any) {
navnLabel.text = "Scan billet."
avCaptureSession.startRunning()
}
/*
// 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.
}
*/
}

Answer 1

The dismiss(animated: true) at the end of your metadataOutput(...) function is being called regardless of what returned.