除非打开Quicktime，否则AVCaptureDevice.devices()不会列出iOS设备

问题描述

我正在尝试在Swift操场上列出使用AVCaptureDevice.devices()连接到我的机器的设备.

I am trying to list the the devices connected to my machine using AVCaptureDevice.devices() in a Swift playground.

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已连接到计算机，这也会给我带来以下结果

This gives me the following result even though my iPhone is connected to my computer

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，如果我启动Quicktime Player，请选择新建电影录制"并选择我的设备作为相机"源，然后列出我的设备

Now something I've noticed is that if I launch Quicktime Player, select New Movie Recording and selecting my device as a Camera source, then my device is listed

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

反正有防止这种情况发生吗?

Is there anyway to prevent this?

推荐答案

您需要稍等片刻，设备才会出现.

You need to wait a bit for the device to appear.

注册AVCaptureDeviceWasConnectedNotification一旦可用，将得到通知.

Register for AVCaptureDeviceWasConnectedNotification to be notified once it becomes available.

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