无视频输出和 [MC] 从公共有效用户设置中读取。 Swift/iOS 11 中的错误

Posted 2023-02-23

【中文标题】无视频输出和 [MC] 从公共有效用户设置中读取。 Swift/iOS 11 中的错误

【英文标题】：No Video Output and [MC] Reading from public effective user settings. Error in Swift/iOS 11

【发布时间】：2017-06-09 01:40:13

【问题描述】：

使用适用于 ios 11 的 Xcode 9 Beta：

我关注了walkthrough，了解如何从 AVCaptureSession 中提取帧，但无法让捕获出现。虽然我在 info.plist 文件中包含了相机权限，但应用程序在打开后似乎停止并且我收到以下错误：

[App Name] 没有 frZQaeyWLUvLjeuEK43hmg 的沙盒访问权限，并且没有适当的权限

[MC] systemgroup.com.apple.configurationprofiles 路径的系统组容器是 /private/var/containers/Shared/SystemGroup/systemgroup.com.apple.configurationprofiles

[MC] 从公共有效用户设置中读取。

这是 FrameExtractor.swift 的代码供参考：

import UIKit
import AVFoundation

protocol FrameExtractorDelegate: class 
    func captured(image: UIImage)


class FrameExtractor: NSObject, AVCaptureVideoDataOutputSampleBufferDelegate 

private let position = AVCaptureDevice.Position.front
private let quality = AVCaptureSession.Preset.medium

private var permissionGranted = false
private let sessionQueue = DispatchQueue(label: "session queue")
private let captureSession = AVCaptureSession()
private let context = CIContext()

weak var delegate: FrameExtractorDelegate?

override init() 
    super.init()
    checkPermission()
    sessionQueue.async  [unowned self] in
        self.configureSession()
        self.captureSession.startRunning()
    


// MARK: AVSession configuration
private func checkPermission() 
    switch AVCaptureDevice.authorizationStatus(for: AVMediaType.video) 
    case .authorized:
        permissionGranted = true
    case .notDetermined:
        requestPermission()
    default:
        permissionGranted = false
    


private func requestPermission() 
    sessionQueue.suspend()
    AVCaptureDevice.requestAccess(for: AVMediaType.video)  [unowned self] granted in
        self.permissionGranted = granted
        self.sessionQueue.resume()
    


private func configureSession() 
    guard permissionGranted else  return 
    captureSession.sessionPreset = quality
    guard let captureDevice = selectCaptureDevice() else  return 
    guard let captureDeviceInput = try? AVCaptureDeviceInput(device: captureDevice) else  return 
    guard captureSession.canAddInput(captureDeviceInput) else  return 
    captureSession.addInput(captureDeviceInput)
    let videoOutput = AVCaptureVideoDataOutput()
    videoOutput.setSampleBufferDelegate(self, queue: DispatchQueue(label: "sample buffer"))
    guard captureSession.canAddOutput(videoOutput) else  return 
    captureSession.addOutput(videoOutput)
    guard let connection = videoOutput.connection(with: AVFoundation.AVMediaType.video) else  return 
    guard connection.isVideoOrientationSupported else  return 
    guard connection.isVideoMirroringSupported else  return 
    connection.videoOrientation = .portrait
    connection.isVideoMirrored = position == .front


private func selectCaptureDevice() -> AVCaptureDevice? 
    return AVCaptureDevice.default(for: AVMediaType.video)
//        return AVCaptureDevice.devices().filter 
//            ($0 as AnyObject).hasMediaType(AVMediaType.video) &&
//                ($0 as AnyObject).position == position
//            .first


// MARK: Sample buffer to UIImage conversion
private func imageFromSampleBuffer(sampleBuffer: CMSampleBuffer) -> UIImage? 
    guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else  return nil 
    let ciImage = CIImage(cvPixelBuffer: imageBuffer)
    guard let cgImage = context.createCGImage(ciImage, from: ciImage.extent) else  return nil 
    return UIImage(cgImage: cgImage)


// MARK: AVCaptureVideoDataOutputSampleBufferDelegate
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) 
    print("Got a Frame!")
    guard let uiImage = imageFromSampleBuffer(sampleBuffer: sampleBuffer) else  return 
    DispatchQueue.main.async  [unowned self] in
        self.delegate?.captured(image: uiImage)
    

对于 ViewController.swift：

import UIKit

class ViewController: UIViewController, FrameExtractorDelegate
@IBOutlet var imageView: UIImageView!
var frameExtractor: FrameExtractor!
override func viewDidLoad() 
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    frameExtractor = FrameExtractor()
    frameExtractor.delegate = self


override func didReceiveMemoryWarning() 
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.


func captured(image: UIImage) 
    imageView.image = image


`

【参考方案1】：

问题在于 captureOutput 中的另一个函数调用。这是 iOS 11 中对 AVCaptureVideoDataOutputSampleBufferDelegate 中的 captureOutput 的新函数调用：

func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) 
    guard let uiImage = imageFromSampleBuffer(sampleBuffer: sampleBuffer) else  return 
    DispatchQueue.main.async  [unowned self] in
        self.delegate?.captured(image: uiImage)
    

注意“didOutput sampleBuffer:”和“didOutputSampleBuffer sampleBuffer:”之间的变化