Presenting UIViewController in UIView - ios

Question

I have recently started with ios development. So currently I have a requirement to present a QR scanner view when a view is clicked. I came through one library https://github.com/twostraws/CodeScanner. but it doesn't work.
I have also the QR code implementation
import AVFoundation
import UIKit
class QRCode: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
var captureSession: AVCaptureSession!
var previewLayer: AVCaptureVideoPreviewLayer!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
view.backgroundColor = UIColor.black
captureSession = AVCaptureSession()
guard let videoCaptureDevice = AVCaptureDevice.default(for: .video) else { return }
let videoInput: AVCaptureDeviceInput
do {
videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice)
} catch {
return
}
if (captureSession.canAddInput(videoInput)) {
captureSession.addInput(videoInput)
} else {
failed()
return
}
let metadataOutput = AVCaptureMetadataOutput()
if (captureSession.canAddOutput(metadataOutput)) {
captureSession.addOutput(metadataOutput)
metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
metadataOutput.metadataObjectTypes = [.ean8, .ean13, .pdf417]
} else {
failed()
return
}
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer.frame = view.layer.bounds
previewLayer.videoGravity = .resizeAspectFill
view.layer.addSublayer(previewLayer)
captureSession.startRunning()
}
func failed() {
let ac = UIAlertController(title: "Scanning not supported", message: "Your device does not support scanning a code from an item. Please use a device with a camera.", preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "OK", style: .default))
present(ac, animated: true)
captureSession = nil
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
if (captureSession?.isRunning == false) {
captureSession.startRunning()
}
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if (captureSession?.isRunning == true) {
captureSession.stopRunning()
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!)
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
captureSession.stopRunning()
if let metadataObject = metadataObjects.first {
guard let readableObject = metadataObject as? AVMetadataMachineReadableCodeObject else { return }
guard let stringValue = readableObject.stringValue else { return }
AudioServicesPlaySystemSound(SystemSoundID(kSystemSoundID_Vibrate))
found(code: stringValue)
}
dismiss(animated: true)
}
func found(code: String) {
print(code)
}
override var prefersStatusBarHidden: Bool {
return true
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
return .portrait
}
}
but I am not able to use this inside a class which inherits UIView
The class definition in which I am trying to use the QRCode class
class A: UIView
I have recently started with ios. Any help would be great

Answer 1

if you want to present a view controller from a presented view controller you can do the following
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func presentPressed(sender: Any) {
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: Bundle.main)
let presentedVC = mainStoryboard.instantiateViewController(withIdentifier: "presentedViewController")
present(presentedVC, animated: true, completion: nil)
}
}
class presentedViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func presentQRVCPressed(sender: Any) {
let mainStoryboard = UIStoryboard(name: "Main", bundle: Bundle.main)
let qrVC = mainStoryboard.instantiateViewController(withIdentifier: "QRViewController")
present(qrVC, animated: true, completion: nil)
}
}
class QRViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
}
otherwise if you want to present a view controller when clicking inside a view, do the following
protocol yourCustomViewDelegate: class {
func presentQRPressed()
}
class yourCustomView: UIView {
// MARK: - Properties
weak var delegate: yourCustomViewDelegate?
#IBAction func presentQRButton(sender: Any) {
if let delegate = delegate {
delegate.presentQRPressed()
}
}
}
class yourViewController: UIViewController, yourCustomViewDelegate {
func presentQRPressed() {
present(yourQRVC, animated: true, completion: nil)
}
}