[英]iOS How to close camera after successfully scanning QR code Swift 4
成功掃描二維碼后如何關閉相機? 我的問題是當我從QR掃描代碼時,掃描后相機未關閉。 我怎么能關閉相機? 我的代碼:
var captureSession: AVCaptureSession!
var previewLayer: AVCaptureVideoPreviewLayer!
var qrCode = String()
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
}
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)
qrCode = code
}
override var prefersStatusBarHidden: Bool {
return true
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
return .portrait
}
打開相機的按鈕:
@IBAction func scanQrButton(_ sender: Any) {
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 = [.qr]
} else {
failed()
return
}
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer.frame = view.layer.bounds
previewLayer.videoGravity = .resizeAspectFill
view.layer.addSublayer(previewLayer)
captureSession.startRunning()
}
正如您所看到的,我有打開相機並掃描QR的代碼,但是我希望在沒有segue的情況下掃描代碼后關閉相機。
你試過這個嗎?
self.captureSession?.stopRunning()
執行掃描以停止捕獲后,可以在會話中使用實例方法stopRunning():
captureSession.stopRunning()
然后使用相機輸出的預覽關閉視圖(這里我認為removeFromSuperlayer()將起作用)。 您可以使用以下方法檢測AVCaptureMetadataOutputObjectsDelegate提供的QR碼掃描時間:
optional func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection)
您還應該按照Apple文檔中的說明將startRunning()放在串行隊列上:
startRunning()方法是一個阻塞調用,可能需要一些時間,因此您應該在串行隊列上執行會話設置,以便不阻止主隊列(這使UI保持響應)。
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