Swift 无法使用AVCaptureDevice发现摄像头

这是我的密码：

if AVCaptureDevice.authorizationStatus(for: AVMediaType.video) == .authorized {
    let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(
        deviceTypes: [.builtInDualCamera],
        mediaType: AVMediaType.video,
        position: .back)
    let captureDevice = deviceDiscoverySession.devices.first
}

结果是空数组（deviceDiscoverySession.devices）。 我在实际设备（iPhone 6+iOS 12.1.2）上运行。

您可以试试

// Find a camera with the specified AVCaptureDevicePosition, returning nil if one is not found
func cameraWithPosition(position: AVCaptureDevice.Position) -> AVCaptureDevice? {
    let discoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: AVMediaType.video, position: .unspecified)
    for device in discoverySession.devices {
        if device.position == position {
            return device
        }
    }

    return nil
}

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使用.builtInWideAngleCamera可以解决此问题。但我想知道这是否适用于所有iOS设备型号？我使用过它，而且它不会突破旧x代和新x代，顺便说一句，您可以在该阵列中指定所有可能的值感谢您的帮助，非常感谢。

if let newCamera = cameraWithPosition(position: .back) {
   //
}