streaming - 如何在 swiftui 中使用实时相机流？

Question

我像这样构建了一个 StreamingView:

struct StreamingView: UIViewRepresentable {

    func updateUIView(_ uiView: UIView, context: UIViewRepresentableContext<StreamingView>) {
        //
    }

    func makeUIView(context: UIViewRepresentableContext<StreamingView>) -> UIView {
        let view = UIView()

        let captureSession = AVCaptureSession()
        captureSession.sessionPreset = .photo

        guard let captureDevice = AVCaptureDevice.default(for: .video) else { return view}
        guard let input = try? AVCaptureDeviceInput(device: captureDevice) else { return view}
        captureSession.addInput(input)

        captureSession.startRunning()

        let previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        view.layer.addSublayer(previewLayer)
        previewLayer.frame = view.frame

        return view
    } 
}

但它没有用。我怎样才能为流媒体构建一个纯粹的 swiftui View ？

Answer 1

试试下面的演示代码

注意:确保完成所有准备工作，例如在功能中打开相机，在 Info.plist 中添加 NSCameraUsageDescription ......并且相机只能在真实设备上测试。

import SwiftUI
import UIKit
import AVFoundation

class PreviewView: UIView {
    private var captureSession: AVCaptureSession?

    init() {
        super.init(frame: .zero)

        var allowedAccess = false
        let blocker = DispatchGroup()
        blocker.enter()
        AVCaptureDevice.requestAccess(for: .video) { flag in
            allowedAccess = flag
            blocker.leave()
        }
        blocker.wait()

        if !allowedAccess {
            print("!!! NO ACCESS TO CAMERA")
            return
        }

        // setup session
        let session = AVCaptureSession()
        session.beginConfiguration()

        let videoDevice = AVCaptureDevice.default(.builtInWideAngleCamera,
            for: .video, position: .unspecified) //alternate AVCaptureDevice.default(for: .video)
        guard videoDevice != nil, let videoDeviceInput = try? AVCaptureDeviceInput(device: videoDevice!), session.canAddInput(videoDeviceInput) else {
            print("!!! NO CAMERA DETECTED")
            return
        }
        session.addInput(videoDeviceInput)
        session.commitConfiguration()
        self.captureSession = session
    }

    override class var layerClass: AnyClass {
        AVCaptureVideoPreviewLayer.self
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    var videoPreviewLayer: AVCaptureVideoPreviewLayer {
        return layer as! AVCaptureVideoPreviewLayer
    }

    override func didMoveToSuperview() {
        super.didMoveToSuperview()

        if nil != self.superview {
            self.videoPreviewLayer.session = self.captureSession
            self.videoPreviewLayer.videoGravity = .resizeAspect
            self.captureSession?.startRunning()
        } else {
            self.captureSession?.stopRunning()
        }
    }
}

struct PreviewHolder: UIViewRepresentable {
    func makeUIView(context: UIViewRepresentableContext<PreviewHolder>) -> PreviewView {
        PreviewView()
    }

    func updateUIView(_ uiView: PreviewView, context: UIViewRepresentableContext<PreviewHolder>) {
    }

    typealias UIViewType = PreviewView
}

struct DemoVideoStreaming: View {
    var body: some View {
        VStack {
            PreviewHolder()
        }.frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .center)
    }
}