除非打开QuickTime，否则未由AvCapturedEvice.devices()列出的iOS设备

Question

我正在尝试在Swift操场中使用AVCaptureDevice.devices()列出与我的计算机连接的设备。

import Cocoa
import Foundation
import AVFoundation
import CoreMediaIO
var prop = CMIOObjectPropertyAddress(
    mSelector: CMIOObjectPropertySelector(kCMIOHardwarePropertyAllowScreenCaptureDevices),
    mScope: CMIOObjectPropertyScope(kCMIOObjectPropertyScopeGlobal),
    mElement: CMIOObjectPropertyElement(kCMIOObjectPropertyElementMaster))
var allow : UInt32 = 1
let dataSize : UInt32 = 4
let zero : UInt32 = 0
CMIOObjectSetPropertyData(CMIOObjectID(kCMIOObjectSystemObject), &prop, zero, nil, dataSize, &allow)

var session = AVCaptureSession()
session.sessionPreset = AVCaptureSession.Preset.low
let devices = AVCaptureDevice.devices()
for device in devices {
    let deviceID = device.uniqueID
    let deviceName = device.localizedName
    print("(deviceID): (deviceName)")
}

即使我的iPhone连接到我的计算机

，这也给了我以下结果

04-52-c7-c1-65-c4:input: Bose Tito
AppleHDAEngineInput:1B,0,1,0:1: Built-in Microphone
CC26311ECFEG1HNBA: FaceTime HD Camera

现在我注意到的是，如果我启动Quicktime Player，请选择新的电影录制并选择设备作为相机源，则列出了我的设备

04-52-c7-c1-65-c4:input: Bose Tito
AppleHDAEngineInput:1B,0,1,0:1: Built-in Microphone
CC26311ECFEG1HNBA: FaceTime HD Camera
12345b7406eeb053e2d5cded2527315d6110a16e: tito

是否有防止这种情况？

Answer 1

您需要等待设备出现。

注册AVCaptureDeviceWasConnectedNotification一旦可用通知。

Answer 2

您是如何实现检查iOS设备准备使用的？我也有同样的问题，并且有一个我正在从事的项目。

目前，如果我有QuickTime打开，它可以正常工作(我还硬编码设备ID，但需要摆脱它(

 override func viewDidLoad() {
    super.viewDidLoad()
    enableDalDevices()
    camera.layer = CALayer()
    let session:AVCaptureSession = AVCaptureSession()
    session.sessionPreset = AVCaptureSession.Preset.high
    let listdevices:Array = (AVCaptureDevice.devices())

   // Grabs iOS device on system change value in array [X] depending on devices connected on your own Mac
    let device:AVCaptureDevice = listdevices[6]
 do {
   try session.addInput(AVCaptureDeviceInput(device: device))
    //Preview
    let previewLayer:AVCaptureVideoPreviewLayer = AVCaptureVideoPreviewLayer(session: session)
    let myView:NSView = self.view
    previewLayer.frame = myView.bounds
    previewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill
    previewLayer.connection?.videoOrientation = AVCaptureVideoOrientation.landscapeRight
    self.camera.layer?.addSublayer(previewLayer)
    session.startRunning()
            print(listdevices)
    } catch {
            }

}

Answer 3

使用 @valerian的答案来帮助答案@adamprocter，这是我最终解决的方法。

override func viewDidLoad() {
    super.viewDidLoad()
    enableDalDevices()
    camera.layer = CALayer()
    let session:AVCaptureSession = AVCaptureSession()
    session.sessionPreset = AVCaptureSession.Preset.high
    let discoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.externalUnknown], mediaType: .muxed, position: .unspecified)
    //You get the devices here and their IDs and do whatever you want
    showDevices(devices: discoverySession.devices)
    //Register for a notification just like @Valerian said earlier
    NotificationCenter.default.addObserver(self, selector: #selector(newDevice), name: NSNotification.Name.AVCaptureDeviceWasConnected, object: nil)
}
@objc func newDevice() {
    let discoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.externalUnknown], mediaType: .muxed, position: .unspecified)
    showDevices(devices: discoverySession.devices)
}