使用 AVFoundation 在 Swift 3.0 中扫描条码或二维码 [英] Scanning Barcode or QR code in Swift 3.0 using AVFoundation
问题描述
我正在关注这个
然后系统在要求用户允许访问时显示目的字符串:
有关它的更多信息，您可以使用这篇文章:
我对您的 BarcodeViewController 做了一些修改以使其正常工作，如下所示:
BarcodeViewController
导入 UIKit导入 AVFoundation协议 BarcodeDelegate {func 条码读取(条码:字符串)}类 BarcodeViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {var 委托:BarcodeDelegate?var videoCaptureDevice: AVCaptureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)var device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)var 输出 = AVCaptureMetadataOutput()var previewLayer:AVCaptureVideoPreviewLayer?var captureSession = AVCaptureSession()变量代码:字符串?覆盖 func viewDidLoad() {super.viewDidLoad()self.view.backgroundColor = UIColor.clearself.setupCamera()}私人 func setupCamera() {让输入=尝试?AVCaptureDeviceInput(设备:videoCaptureDevice)如果 self.captureSession.canAddInput(input) {self.captureSession.addInput(输入)}self.previewLayer = AVCaptureVideoPreviewLayer(会话:captureSession)如果让 videoPreviewLayer = self.previewLayer {videoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFillvideoPreviewLayer.frame = self.view.boundsview.layer.addSublayer(videoPreviewLayer)}让元数据输出 = AVCaptureMetadataOutput()如果 self.captureSession.canAddOutput(metadataOutput) {self.captureSession.addOutput(metadataOutput)metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)metadataOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode, AVMetadataObjectTypeEAN13Code]} 别的 {print("无法添加元数据输出")}}覆盖 func viewWillAppear(_ 动画:布尔){super.viewWillAppear(动画)if (captureSession.isRunning == false) {captureSession.startRunning();}}覆盖 func viewWillDisappear(_ 动画:布尔){super.viewWillDisappear(动画)if (captureSession.isRunning == true) {captureSession.stopRunning();}}func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {//这是读取代码时调用的委托方法对于 metadataObjects 中的元数据 {让 readableObject = metadata as!AVMetadataMachineReadableCodeObject让代码 = readableObject.stringValueself.dismiss(动画:true，完成:nil)self.delegate?.barcodeReaded(barcode: code!)打印(代码！)}}}重点之一是在viewWillAppear(:)和viewWillDisappear(:)中声明全局变量并启动和停止captureSession代码>方法.在您之前的代码中，我认为它根本没有被调用，因为它从未进入处理条形码的方法中.
希望对你有帮助.
I am following this tutorial and tried to convert codes form Swift 2.0 to 3.0. But when I launched the application, the app doesn't work! I mean, nothing happens! Here is my code:
ViewController:
class ViewController: UIViewController ,BarcodeDelegate {
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let barcodeViewController: BarcodeViewController = segue.destination as! BarcodeViewController
barcodeViewController.delegate = self
}
func barcodeReaded(barcode: String) {
codeTextView.text = barcode
print(barcode)
}
}
BarcodeVC:
import AVFoundation
protocol BarcodeDelegate {
func barcodeReaded(barcode: String)
}
class BarcodeViewController: UIViewController,AVCaptureMetadataOutputObjectsDelegate {
var delegate: BarcodeDelegate?
var captureSession: AVCaptureSession!
var code: String?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
print("works")
self.captureSession = AVCaptureSession();
let videoCaptureDevice: AVCaptureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
do {
let videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice)
if self.captureSession.canAddInput(videoInput) {
self.captureSession.addInput(videoInput)
} else {
print("Could not add video input")
}
let metadataOutput = AVCaptureMetadataOutput()
if self.captureSession.canAddOutput(metadataOutput) {
self.captureSession.addOutput(metadataOutput)
metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
metadataOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode,AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypePDF417Code]
} else {
print("Could not add metadata output")
}
let previewLayer = AVCaptureVideoPreviewLayer(session: self.captureSession)
previewLayer?.frame = self.view.layer.bounds
self.view.layer .addSublayer(previewLayer!)
self.captureSession.startRunning()
} catch let error as NSError {
print("Error while creating vide input device: (error.localizedDescription)")
}
}
//I THINK THIS METHOD NOT CALL !
private func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
// This is the delegate'smethod that is called when a code is readed
for metadata in metadataObjects {
let readableObject = metadata as! AVMetadataMachineReadableCodeObject
let code = readableObject.stringValue
// If the code is not empty the code is ready and we call out delegate to pass the code.
if code!.isEmpty {
print("is empty")
}else {
self.captureSession.stopRunning()
self.dismiss(animated: true, completion: nil)
self.delegate?.barcodeReaded(barcode: code!)
}
}
}
Here is the output:
2016-09-17 18:10:26.000919 BarcodeScaning[2610:674253] [MC] System group container for systemgroup.com.apple.configurationprofiles path is /private/var/containers/Shared/SystemGroup/systemgroup.com.apple.configurationprofiles 2016-09-17 18:10:26.007782 BarcodeScaning[2610:674253] [MC] Reading from public effective user settings.
The first step needs to be declare access to any user private data types that is a new requirement in iOS 10. You can do it by adding a usage key to your app’s Info.plist together with a purpose string.
Because if you are using one of the following frameworks and fail to declare the usage your app will crash when it first makes the access:
Contacts, Calendar, Reminders, Photos, Bluetooth Sharing, Microphone, Camera, Location, Health, HomeKit, Media Library, Motion, CallKit, Speech Recognition, SiriKit, TV Provider.
To avoid the crash you need to add the suggested key to Info.plist:
And then the system shows the purpose string when asking the user to allow access:
For more information about it you can use this article:
I have done a little modifications to your BarcodeViewController to make it work properly as you can see below:
BarcodeViewController
import UIKit
import AVFoundation
protocol BarcodeDelegate {
func barcodeReaded(barcode: String)
}
class BarcodeViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
var delegate: BarcodeDelegate?
var videoCaptureDevice: AVCaptureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
var device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
var output = AVCaptureMetadataOutput()
var previewLayer: AVCaptureVideoPreviewLayer?
var captureSession = AVCaptureSession()
var code: String?
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = UIColor.clear
self.setupCamera()
}
private func setupCamera() {
let input = try? AVCaptureDeviceInput(device: videoCaptureDevice)
if self.captureSession.canAddInput(input) {
self.captureSession.addInput(input)
}
self.previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
if let videoPreviewLayer = self.previewLayer {
videoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
videoPreviewLayer.frame = self.view.bounds
view.layer.addSublayer(videoPreviewLayer)
}
let metadataOutput = AVCaptureMetadataOutput()
if self.captureSession.canAddOutput(metadataOutput) {
self.captureSession.addOutput(metadataOutput)
metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
metadataOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode, AVMetadataObjectTypeEAN13Code]
} else {
print("Could not add metadata output")
}
}
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();
}
}
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
// This is the delegate's method that is called when a code is read
for metadata in metadataObjects {
let readableObject = metadata as! AVMetadataMachineReadableCodeObject
let code = readableObject.stringValue
self.dismiss(animated: true, completion: nil)
self.delegate?.barcodeReaded(barcode: code!)
print(code!)
}
}
}
One of the important points was to declare the global variables and start and stop the captureSession inside the viewWillAppear(:) and viewWillDisappear(:) methods. In your previous code I think it was not called at all as it never enter inside the method to process the barcode.
I hope this help you.
这篇关于使用 AVFoundation 在 Swift 3.0 中扫描条码或二维码的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
