我的应用程序中已经实现了条形码扫描。 在检测到条形码后，我停止捕获会话以允许处理条形码。 但是，在处理完条形码后，我希望扫描控制器保持打开状态并继续扫描下一个条形码。 我原本以为启动捕获会话（startRunning()）就可以做到这一点，但图像仍然被冻结。 如何再次启动捕获会话？
4个回答
13
使用此代码停止会话
self.session.stopRunning()
要重新开始，请使用此代码
self.session.startRunning()
这里是实现条形码扫描器的所有代码...
import UIKit
import AVFoundation
class ViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
let session : AVCaptureSession = AVCaptureSession()
var previewLayer : AVCaptureVideoPreviewLayer!
var highlightView : UIView = UIView()
override func viewDidLoad() {
super.viewDidLoad()
// Allow the view to resize freely
self.highlightView.autoresizingMask =
UIViewAutoresizing.FlexibleTopMargin |
UIViewAutoresizing.FlexibleBottomMargin |
UIViewAutoresizing.FlexibleLeftMargin |
UIViewAutoresizing.FlexibleRightMargin
// Select the color you want for the completed scan reticle
self.highlightView.layer.borderColor = UIColor.greenColor().CGColor
self.highlightView.layer.borderWidth = 3
// Add it to our controller's view as a subview.
self.view.addSubview(self.highlightView)
// For the sake of discussion this is the camera
let device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
// Create a nilable NSError to hand off to the next method.
// Make sure to use the "var" keyword and not "let"
var error : NSError? = nil
let input : AVCaptureDeviceInput? =
AVCaptureDeviceInput.deviceInputWithDevice(device, error: &error)
as? AVCaptureDeviceInput
// If our input is not nil then add it to the session, otherwise we're kind of done!
if input != nil {
session.addInput(input)
} else {
// This is fine for a demo, do something real with this in your app. :)
println(error)
}
let output = AVCaptureMetadataOutput()
output.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
session.addOutput(output)
output.metadataObjectTypes = output.availableMetadataObjectTypes
previewLayer =
AVCaptureVideoPreviewLayer.layerWithSession(session)
as! AVCaptureVideoPreviewLayer
previewLayer.frame = self.view.bounds
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
self.view.layer.addSublayer(previewLayer)
// Start the scanner. You'll have to end it yourself later.
session.startRunning()
}
// This is called when we find a known barcode type with the camera.
func captureOutput(
captureOutput: AVCaptureOutput!,
didOutputMetadataObjects metadataObjects: [AnyObject]!,
fromConnection connection: AVCaptureConnection!) {
var highlightViewRect = CGRectZero
var barCodeObject : AVMetadataObject!
var detectionString : String!
let barCodeTypes = [AVMetadataObjectTypeUPCECode,
AVMetadataObjectTypeCode39Code,
AVMetadataObjectTypeCode39Mod43Code,
AVMetadataObjectTypeEAN13Code,
AVMetadataObjectTypeEAN8Code,
AVMetadataObjectTypeCode93Code,
AVMetadataObjectTypeCode128Code,
AVMetadataObjectTypePDF417Code,
AVMetadataObjectTypeQRCode,
AVMetadataObjectTypeAztecCode]
// The scanner is capable of capturing multiple 2-dimensional barcodes in one scan.
for metadata in metadataObjects {
for barcodeType in barCodeTypes {
if metadata.type == barcodeType {
barCodeObject = self.previewLayer.transformedMetadataObjectForMetadataObject(metadata as! AVMetadataMachineReadableCodeObject)
highlightViewRect = barCodeObject.bounds
detectionString = (metadata as! AVMetadataMachineReadableCodeObject).stringValue
self.session.stopRunning()
self.alert(detectionString)
break
}
}
}
println(detectionString)
self.highlightView.frame = highlightViewRect
self.view.bringSubviewToFront(self.highlightView)
}
func alert(Code: String){
let actionSheet:UIAlertController =
UIAlertController(
title: "Barcode",
message: "\(Code)",
preferredStyle: UIAlertControllerStyle.Alert)
// for alert add .Alert instead of .Action Sheet
// start copy
let firstAlertAction:UIAlertAction =
UIAlertAction(
title: "OK",
style: UIAlertActionStyle.Default,
handler: { (alertAction: UIAlertAction!) in
// action when pressed
self.session.startRunning()
})
actionSheet.addAction(firstAlertAction)
// end copy
self.presentViewController(actionSheet, animated: true, completion: nil)
}
}
- nachshon f
3
如果这个方法有效，请不要忘记将此答案标记为正确的答案。 - nachshon f
我做的事情基本上是一样的，但是我的两行代码被交换了。我先将结果字符串发送到处理程序，然后停止会话。这样就无法重新启动。如果在将结果发送到处理程序之前停止会话，则可以正常工作。 - Floyd Resler
在此添加了Swift 3版本：https://dev59.com/Z10Z5IYBdhLWcg3wtSA8#41512546 - mkhoshpour
10
我已经编辑了上面的代码以适应Swift 2.0：
import UIKit
import AVFoundation
class BarCodeViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
let session : AVCaptureSession = AVCaptureSession()
var previewLayer : AVCaptureVideoPreviewLayer!
@IBOutlet weak var highlightView: UIView!
override func viewDidLoad() {
super.viewDidLoad()
// Select the color you want for the completed scan reticle
self.highlightView.layer.borderColor = UIColor.greenColor().CGColor
self.highlightView.layer.borderWidth = 3
// Add it to our controller's view as a subview.
self.view.addSubview(self.highlightView)
// For the sake of discussion this is the camera
let device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
// Create a nilable NSError to hand off to the next method.
// Make sure to use the "var" keyword and not "let"
var error : NSError? = nil
var input: AVCaptureDeviceInput = AVCaptureDeviceInput()
do {
input = try AVCaptureDeviceInput(device: device) as AVCaptureDeviceInput
} catch let myJSONError {
print(myJSONError)
}
// If our input is not nil then add it to the session, otherwise we're kind of done!
if input != AVCaptureDeviceInput() {
session.addInput(input)
}
else {
// This is fine for a demo, do something real with this in your app. :)
print(error)
}
let output = AVCaptureMetadataOutput()
output.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
session.addOutput(output)
output.metadataObjectTypes = output.availableMetadataObjectTypes
previewLayer = AVCaptureVideoPreviewLayer(session: session)
previewLayer.frame = self.view.bounds
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
self.view.layer.addSublayer(previewLayer)
// Start the scanner. You'll have to end it yourself later.
session.startRunning()
}
// This is called when we find a known barcode type with the camera.
func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
var highlightViewRect = CGRectZero
var barCodeObject : AVMetadataObject!
var detectionString : String!
let barCodeTypes = [AVMetadataObjectTypeUPCECode,
AVMetadataObjectTypeCode39Code,
AVMetadataObjectTypeCode39Mod43Code,
AVMetadataObjectTypeEAN13Code,
AVMetadataObjectTypeEAN8Code,
AVMetadataObjectTypeCode93Code,
AVMetadataObjectTypeCode128Code,
AVMetadataObjectTypePDF417Code,
AVMetadataObjectTypeQRCode,
AVMetadataObjectTypeAztecCode
]
// The scanner is capable of capturing multiple 2-dimensional barcodes in one scan.
for metadata in metadataObjects {
for barcodeType in barCodeTypes {
if metadata.type == barcodeType {
barCodeObject = self.previewLayer.transformedMetadataObjectForMetadataObject(metadata as! AVMetadataMachineReadableCodeObject)
highlightViewRect = barCodeObject.bounds
detectionString = (metadata as! AVMetadataMachineReadableCodeObject).stringValue
self.session.stopRunning()
self.alert(detectionString)
break
}
}
}
print(detectionString)
self.highlightView.frame = highlightViewRect
self.view.bringSubviewToFront(self.highlightView)
}
func alert(Code: String){
let actionSheet:UIAlertController = UIAlertController(title: "Barcode", message: "\(Code)", preferredStyle: UIAlertControllerStyle.Alert)
// for alert add .Alert instead of .Action Sheet
// start copy
let firstAlertAction:UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: {
(alertAction:UIAlertAction!) in
// action when pressed
self.session.startRunning()
})
actionSheet.addAction(firstAlertAction)
// end copy
self.presentViewController(actionSheet, animated: true, completion: nil)
}
}
- mkhoshpour
4
Swift 3.0 版本:
import UIKit
import AVFoundation
class BarCodeViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
let session : AVCaptureSession = AVCaptureSession()
var previewLayer : AVCaptureVideoPreviewLayer!
@IBOutlet weak var highlightView: UIView!
override func viewDidLoad() {
super.viewDidLoad()
self.highlightView.layer.borderColor = UIColor.green.cgColor
self.highlightView.layer.borderWidth = 3
// Add it to our controller's view as a subview.
self.view.addSubview(self.highlightView)
// For the sake of discussion this is the camera
let device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
// Create a nilable NSError to hand off to the next method.
// Make sure to use the "var" keyword and not "let"
var error : NSError? = nil
var input: AVCaptureDeviceInput = AVCaptureDeviceInput()
do {
input = try AVCaptureDeviceInput(device: device) as AVCaptureDeviceInput
} catch let myJSONError {
print(myJSONError)
}
// If our input is not nil then add it to the session, otherwise we're kind of done!
if input != AVCaptureDeviceInput() {
session.addInput(input)
}
else {
// This is fine for a demo, do something real with this in your app. :)
print(error!)
}
let output = AVCaptureMetadataOutput()
output.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
session.addOutput(output)
output.metadataObjectTypes = output.availableMetadataObjectTypes
previewLayer = AVCaptureVideoPreviewLayer(session: session)
previewLayer.frame = self.view.bounds
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
self.view.layer.addSublayer(previewLayer)
// Start the scanner. You'll have to end it yourself later.
session.startRunning()
}
// This is called when we find a known barcode type with the camera.
@nonobjc func captureOutput(
captureOutput: AVCaptureOutput!,
didOutputMetadataObjects metadataObjects: [AnyObject]!,
fromConnection connection: AVCaptureConnection!) {
var highlightViewRect = CGRect()
var barCodeObject : AVMetadataObject!
var detectionString : String!
let barCodeTypes = [AVMetadataObjectTypeUPCECode,
AVMetadataObjectTypeCode39Code,
AVMetadataObjectTypeCode39Mod43Code,
AVMetadataObjectTypeEAN13Code,
AVMetadataObjectTypeEAN8Code,
AVMetadataObjectTypeCode93Code,
AVMetadataObjectTypeCode128Code,
AVMetadataObjectTypePDF417Code,
AVMetadataObjectTypeQRCode,
AVMetadataObjectTypeAztecCode]
// The scanner is capable of capturing multiple 2-dimensional barcodes in one scan.
for metadata in metadataObjects {
for barcodeType in barCodeTypes {
if metadata.type == barcodeType {
barCodeObject = self.previewLayer.transformedMetadataObject(for: metadata as! AVMetadataMachineReadableCodeObject)
highlightViewRect = barCodeObject.bounds
detectionString = (metadata as! AVMetadataMachineReadableCodeObject).stringValue
self.session.stopRunning()
self.alert(Code: detectionString)
break
}
}
}
print(detectionString)
self.highlightView.frame = highlightViewRect
self.view.bringSubview(toFront: self.highlightView)
}
func alert(Code: String){
let actionSheet:UIAlertController = UIAlertController(title: "Barcode", message: "\(Code)", preferredStyle: UIAlertControllerStyle.alert)
// for alert add .Alert instead of .Action Sheet
// start copy
let firstAlertAction:UIAlertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: { (alertAction: UIAlertAction!) in
// action when pressed
self.session.startRunning()
})
actionSheet.addAction(firstAlertAction)
// end copy
self.present(actionSheet, animated: true, completion: nil)
}
}
- mkhoshpour
-1
Swift 5 更新
func captureOutput(
captureOutput: AVCaptureOutput,
didOutputMetadataObjects metadataObjects: [AnyObject],
fromConnection connection: AVCaptureConnection,
barCodeType: [AVMetadataObject.ObjectType]) -> String? {
var detectionString: String?
var highlightViewRect = CGRect()
let barCodeTypes = barCodeType
if let metadataObject = metadataObjects.first {
for barcodeType in barCodeTypes {
if metadataObject.type == barcodeType {
guard let readableObject = metadataObject as? AVMetadataMachineReadableCodeObject else { return String()}
guard let barCodeObject = self.previewLayer.transformedMetadataObject(for: readableObject) else { return String()}
highlightViewRect = barCodeObject.bounds
detectionString = readableObject.stringValue
self.captureSession.stopRunning()
break
}
}
}
self.qrView.frame = highlightViewRect
self.view.bringSubviewToFront(self.qrView)
return detectionString
}
- Aalaa
1
由于这只是已接受答案的部分移植，因此请勿点踩。 - javi_swift
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