ios - 条码扫描后屏幕冻结
问题描述
我正在学习 SWIFT 并变得更好。我拥有的条形码应用程序可以工作,但它会无休止地扫描条形码,直到我强制弹出屏幕“确定”、“取消”以接受或拒绝扫描。在研究中,我发现了非常相似的代码(如下所示)。所以我创建了一个只有一个视图控制器的测试项目来尝试这段代码。它工作得很好,但一旦扫描条形码就会冻结。我的意图是取消冻结屏幕,接受并保存它并允许用户扫描更多条形码。任何帮助是极大的赞赏。我尝试在找到的行下方停止扫描(代码:),但它无助于解冻。我可能是错的,但我怀疑 viewilldisapper 永远不会在这里被调用。
import AVFoundation
import UIKit
class ScannerViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
var captureSession: AVCaptureSession!
var previewLayer: AVCaptureVideoPreviewLayer!
override func viewDidLoad() {
super.viewDidLoad()
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()
}
}
func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], 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
}
}
编辑代码:
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)
barcodeValue = stringValue
}
// dismiss(animated: true)
previewLayer.removeFromSuperlayer()
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer.frame = view.layer.bounds
previewLayer.videoGravity = .resizeAspectFill
view.layer.addSublayer(previewLayer)
let alertController = UIAlertController(title: "Barcode Scanned", message: barcodeValue!, preferredStyle: .alert)
alertController.addAction(UIAlertAction(title: "OK", style: .default, handler: {(alert: UIAlertAction!) in self.restartScan()}))
alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler:nil))
present(alertController, animated: true, completion: nil)
//captureSession.startRunning()
}
func found(code: String) {
print(code)
}
func restartScan() {
captureSession.startRunning()
}
解决方案
这不是冻结,当检测到第一个条形码时,您需要captureSession.stopRunning()
在内部停止该过程func metadataOutput(_ output: AVCaptureMetadataOutput
previewLayer.removeFromSuperlayer()
而不是这个
dismiss(animated: true)
因为它是一个层而不是一个 vc 来消除您之前添加的
view.layer.addSublayer(previewLayer)
注意:您的视图背景为黑色
推荐阅读
- r - 将数值向量更改为特定日期
- r - 单个csv(在文件列表中)和R中数据框的渐进列之间的内部连接
- c# - 使用 EFCore.BulkExtensions 时如何避免向 db 添加重复数据?
- android - 在 Pixel 3A 设备上使用 mediacodec android 将 ARGB_8888 位图编码为视频文件失败
- python - 授予在 Apache2 ubuntu 上运行的 Python Flask 应用程序的权限
- laravel - Npm Run Dev 无法正常工作 字体真棒 Laravel 8
- python - 根据 Python3 中的 excel 生成的列表对复制文件和重命名进行故障排除
- python - 从另一个类对象引用一个类对象
- java - Apache derby db 错误“请求的企业集团 (1.744) 不存在”
- javascript - 如何在反应中将数据作为对象数组提交