//1.捕获管理
let session = AVCaptureSession()
1.一个完整的相机有一个AVCaptureSession管理,它负责从输入设备端捕获输入源,并向输出端输出捕获的数据,所以我们需要初始化一个捕获管理会话AVCaptureSession
2.请求权限,并添加输入源:相机需要使用的输入源是摄像头,所以我们需要找到一个AVCaptureDevice的相机实例。并且我们需要在调用之前,请求权限。
var backCameraDevice:AVCaptureDevice? = nil
var frontCameraDevice:AVCaptureDevice? = nil
let status = AVCaptureDevice.authorizationStatus(for: .video)
switch status {
case .notDetermined:
AVCaptureDevice.requestAccess(for: .video) { (granted) in
if granted {
backCameraDevice = AVCaptureDevice.DiscoverySession.init(deviceTypes: [.builtInWideAngleCamera], mediaType: .audio, position: .back).devices[0]
frontCameraDevice = AVCaptureDevice.DiscoverySession.init(deviceTypes: [.builtInWideAngleCamera], mediaType: .video, position: .front).devices[0]
}