[英]How to initiate iPhone camera properly
I`m trying to build simple app which will scan barcodes and having this piece of code 我正在尝试构建一个简单的应用程序,它将扫描条形码并拥有这段代码
var captureSession: AVCaptureSession?
var videoPreviewLayer: AVCaptureVideoPreviewLayer?
var codeView: UIView?
override func viewDidLoad() {
super.viewDidLoad()
let discoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInDualCamera], mediaType: AVMediaType.video, position: .back)
guard let captureDevice = discoverySession.devices.first else {
print("Camre initialization faild.")
return
}
do {
let input = try AVCaptureDeviceInput(device: captureDevice)
captureSession?.addInput(input)
let captureMetadataOutput = AVCaptureMetadataOutput()
captureSession?.addOutput(captureMetadataOutput)
captureMetadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
captureMetadataOutput.metadataObjectTypes = [AVMetadataObject.ObjectType.qr]
videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession!)
videoPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
videoPreviewLayer?.frame = view.layer.bounds
view.layer.addSublayer(videoPreviewLayer!)
captureSession?.startRunning()
} catch let error as NSError {
print("Error \(error.localizedDescription)")
}
}
I run application on physical device Xs Max with iOS 12.3.1 and it unexpectadly crashes on the line 我使用iOS 12.3.1在物理设备Xs Max上运行应用程序,并且它无意中崩溃了
captureMetadataOutput.metadataObjectTypes = [AVMetadataObject.ObjectType.qr]
with error "libc++abi.dylib: terminating with uncaught exception of type NSException" 错误“libc ++ abi.dylib:以NSException类型的未捕获异常终止”
import AVFoundation
var captureSession: AVCaptureSession!
var videoPreviewLayer: AVCaptureVideoPreviewLayer!
override func viewDidLoad() {
super.viewDidLoad()
captureSession = AVCaptureSession()
guard let captureDevice = AVCaptureDevice.default(for: .video) else {return}
let videoInput: AVCaptureDeviceInput
do {
videoInput = try AVCaptureDeviceInput(device: captureDevice)
} catch {
// handle error
return
}
if (captureSession.canAddInput(videoInput)) {
captureSession.addInput(videoInput)
} else {
// handle error
return
}
let metadataOutput = AVCaptureMetadataOutput()
if (captureSession.canAddOutput(metadataOutput)) {
captureSession.addOutput(metadataOutput)
metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
metadataOutput.metadataObjectTypes = [.qr]
} else {
// handle error
return
}
videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
videoPreviewLayer.frame = view.layer.bounds
videoPreviewLayer.videoGravity = .resizeAspectFill
view.layer.addSublayer(videoPreviewLayer)
captureSession.startRunning()
}
This code should help you, also remember to add AVCaptureMetadataOutputObjectsDelegate 此代码应该对您有所帮助,还要记得添加AVCaptureMetadataOutputObjectsDelegate
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