Eine weitere native iOS-Lösung mit Swift 4 und Xcode 9 finden Sie unten. Natives AVFoundationFramework, das in dieser Lösung verwendet wird.
Der erste Teil ist eine Unterklasse, für UIViewControllerdie entsprechende Setup- und Handlerfunktionen vorhanden sind AVCaptureSession.
import UIKit
import AVFoundation
class BarCodeScannerViewController: UIViewController {
let captureSession = AVCaptureSession()
var videoPreviewLayer: AVCaptureVideoPreviewLayer!
var initialized = false
let barCodeTypes = [AVMetadataObject.ObjectType.upce,
AVMetadataObject.ObjectType.code39,
AVMetadataObject.ObjectType.code39Mod43,
AVMetadataObject.ObjectType.code93,
AVMetadataObject.ObjectType.code128,
AVMetadataObject.ObjectType.ean8,
AVMetadataObject.ObjectType.ean13,
AVMetadataObject.ObjectType.aztec,
AVMetadataObject.ObjectType.pdf417,
AVMetadataObject.ObjectType.itf14,
AVMetadataObject.ObjectType.dataMatrix,
AVMetadataObject.ObjectType.interleaved2of5,
AVMetadataObject.ObjectType.qr]
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
setupCapture()
// set observer for UIApplicationWillEnterForeground, so we know when to start the capture session again
NotificationCenter.default.addObserver(self,
selector: #selector(willEnterForeground),
name: .UIApplicationWillEnterForeground,
object: nil)
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
// this view is no longer topmost in the app, so we don't need a callback if we return to the app.
NotificationCenter.default.removeObserver(self,
name: .UIApplicationWillEnterForeground,
object: nil)
}
// This is called when we return from another app to the scanner view
@objc func willEnterForeground() {
setupCapture()
}
func setupCapture() {
var success = false
var accessDenied = false
var accessRequested = false
let authorizationStatus = AVCaptureDevice.authorizationStatus(for: .video)
if authorizationStatus == .notDetermined {
// permission dialog not yet presented, request authorization
accessRequested = true
AVCaptureDevice.requestAccess(for: .video,
completionHandler: { (granted:Bool) -> Void in
self.setupCapture();
})
return
}
if authorizationStatus == .restricted || authorizationStatus == .denied {
accessDenied = true
}
if initialized {
success = true
} else {
let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera,
.builtInTelephotoCamera,
.builtInDualCamera],
mediaType: .video,
position: .unspecified)
if let captureDevice = deviceDiscoverySession.devices.first {
do {
let videoInput = try AVCaptureDeviceInput(device: captureDevice)
captureSession.addInput(videoInput)
success = true
} catch {
NSLog("Cannot construct capture device input")
}
} else {
NSLog("Cannot get capture device")
}
}
if success {
DispatchQueue.global().async {
self.captureSession.startRunning()
DispatchQueue.main.async {
let captureMetadataOutput = AVCaptureMetadataOutput()
self.captureSession.addOutput(captureMetadataOutput)
let newSerialQueue = DispatchQueue(label: "barCodeScannerQueue") // in iOS 11 you can use main queue
captureMetadataOutput.setMetadataObjectsDelegate(self, queue: newSerialQueue)
captureMetadataOutput.metadataObjectTypes = self.barCodeTypes
self.videoPreviewLayer = AVCaptureVideoPreviewLayer(session: self.captureSession)
self.videoPreviewLayer.videoGravity = .resizeAspectFill
self.videoPreviewLayer.frame = self.view.layer.bounds
self.view.layer.addSublayer(self.videoPreviewLayer)
}
}
initialized = true
} else {
// Only show a dialog if we have not just asked the user for permission to use the camera. Asking permission
// sends its own dialog to th user
if !accessRequested {
// Generic message if we cannot figure out why we cannot establish a camera session
var message = "Cannot access camera to scan bar codes"
#if (arch(i386) || arch(x86_64)) && (!os(macOS))
message = "You are running on the simulator, which does not hae a camera device. Try this on a real iOS device."
#endif
if accessDenied {
message = "You have denied this app permission to access to the camera. Please go to settings and enable camera access permission to be able to scan bar codes"
}
let alertPrompt = UIAlertController(title: "Cannot access camera", message: message, preferredStyle: .alert)
let confirmAction = UIAlertAction(title: "OK", style: .default, handler: { (action) -> Void in
self.navigationController?.popViewController(animated: true)
})
alertPrompt.addAction(confirmAction)
self.present(alertPrompt, animated: true, completion: nil)
}
}
}
func handleCapturedOutput(metadataObjects: [AVMetadataObject]) {
if metadataObjects.count == 0 {
return
}
guard let metadataObject = metadataObjects.first as? AVMetadataMachineReadableCodeObject else {
return
}
if barCodeTypes.contains(metadataObject.type) {
if let metaDataString = metadataObject.stringValue {
captureSession.stopRunning()
displayResult(code: metaDataString)
return
}
}
}
func displayResult(code: String) {
let alertPrompt = UIAlertController(title: "Bar code detected", message: code, preferredStyle: .alert)
if let url = URL(string: code) {
let confirmAction = UIAlertAction(title: "Launch URL", style: .default, handler: { (action) -> Void in
UIApplication.shared.open(url, options: [:], completionHandler: { (result) in
if result {
NSLog("opened url")
} else {
let alertPrompt = UIAlertController(title: "Cannot open url", message: nil, preferredStyle: .alert)
let confirmAction = UIAlertAction(title: "OK", style: .default, handler: { (action) -> Void in
})
alertPrompt.addAction(confirmAction)
self.present(alertPrompt, animated: true, completion: {
self.setupCapture()
})
}
})
})
alertPrompt.addAction(confirmAction)
}
let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: { (action) -> Void in
self.setupCapture()
})
alertPrompt.addAction(cancelAction)
present(alertPrompt, animated: true, completion: nil)
}
}
Der zweite Teil ist die Erweiterung unserer UIViewControllerUnterklasse, AVCaptureMetadataOutputObjectsDelegatein der wir die erfassten Ausgaben erfassen.
extension BarCodeScannerViewController: AVCaptureMetadataOutputObjectsDelegate {
func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
handleCapturedOutput(metadataObjects: metadataObjects)
}
}
Update für Swift 4.2
.UIApplicationWillEnterForegroundändert sich als UIApplication.willEnterForegroundNotification.