ios - 无法让自定义相机显示正在捕获的内容的预览

Question

我正在尝试开发自定义相机。我的代码如下。我目前无法让应用程序显示正在捕获的内容？我正在使用我的实体 iPhone 来测试该应用。

我正在尝试开发自定义相机。我的代码如下。我目前无法让应用程序显示正在捕获的内容？我正在使用我的实体 iPhone 来测试该应用。

屏幕截图:

Xcode 11。目标 12.4

我的代码:

class CameraViewController: UIViewController, AVCaptureVideoDataOutputSampleBufferDelegate {
var margin: UILayoutGuide!
var captureSession: AVCaptureSession!
var previewLayer: AVCaptureVideoPreviewLayer!
let topSection: UIView = {
    let view = UIView()
    view.translatesAutoresizingMaskIntoConstraints = false
    view.backgroundColor = UIColor.yellow
    return view
}()
let cameraView: UIView = {
    let view = UIView()
    view.translatesAutoresizingMaskIntoConstraints = false
    //view.backgroundColor = UIColor.black
    return view
}()
let bottomSection: UIView = {
    let view = UIView()
    view.translatesAutoresizingMaskIntoConstraints = false
    view.backgroundColor = UIColor.green
    return view
}()

override func viewDidLoad() {
    super.viewDidLoad()

    setup()
}

private func setup(){
    view.backgroundColor = UIColor.white
    margin = view.layoutMarginsGuide
    captureSession = AVCaptureSession.init()

    view.addSubview(topSection)
    view.addSubview(bottomSection)
    view.addSubview(cameraView)
    setupSectionLayouts()

    setupCameraCapture()
}

private func setupCameraCapture(){

    captureSession.beginConfiguration()

    // Configure input
    let videoDevice = AVCaptureDevice.default(for: .video)
    guard
        let videoDeviceInput = try? AVCaptureDeviceInput.init(device: videoDevice!) as AVCaptureInput,
        captureSession.canAddInput(videoDeviceInput)
        else{
            print("unable to add videoDeviceInput")
            return
    }
    captureSession.addInput(videoDeviceInput)

    // configure output
    let videoOutput = AVCaptureVideoDataOutput.init()
    guard captureSession.canAddOutput(videoOutput) else {
        print("unable add videoOutput")
        return

    }
    videoOutput.setSampleBufferDelegate(self, queue: DispatchQueue.init(label: "videoQueue"))
    captureSession.addOutput(videoOutput)
    captureSession.commitConfiguration()
    captureSession.startRunning()

    guard let session = captureSession else {
        print("no captureSession")
        return

    }
    previewLayer = AVCaptureVideoPreviewLayer.init(session: session)
    previewLayer.frame = cameraView.bounds
    cameraView.layer.insertSublayer(previewLayer, at: 0)
}



}

// Layout
extension CameraViewController{

private func setupSectionLayouts(){

    topSection.heightAnchor.constraint(equalTo: margin.heightAnchor, multiplier: 0.1).isActive = true
    topSection.topAnchor.constraint(equalTo: margin.topAnchor).isActive = true
    topSection.leadingAnchor.constraint(equalTo: margin.leadingAnchor).isActive = true
    topSection.trailingAnchor.constraint(equalTo: margin.trailingAnchor).isActive = true

    bottomSection.heightAnchor.constraint(equalTo: margin.heightAnchor, multiplier: 0.15).isActive = true
    bottomSection.bottomAnchor.constraint(equalTo: margin.bottomAnchor).isActive = true
    bottomSection.leadingAnchor.constraint(equalTo: margin.leadingAnchor).isActive = true
    bottomSection.trailingAnchor.constraint(equalTo: margin.trailingAnchor).isActive = true

    cameraView.topAnchor.constraint(equalTo: topSection.bottomAnchor).isActive = true
    cameraView.bottomAnchor.constraint(equalTo: bottomSection.topAnchor).isActive = true
    cameraView.leadingAnchor.constraint(equalTo: margin.leadingAnchor).isActive = true
    cameraView.trailingAnchor.constraint(equalTo: margin.trailingAnchor).isActive = true

}
}

Answer 1

你的问题在这里

 previewLayer.frame = cameraView.bounds

由于 cameraView.bounds 尚未在 viewDidLoad 中计算，尝试

override  func viewDidLayoutSubviews() {
   super.viewDidLayoutSubviews()
   previewLayer.frame = cameraView.bounds
}