如何使用 AVCaptureDeviceDiscoverySession 获取前置摄像头、后置摄像头和音频

Question

Before iOS 10 came out I was using the following code to get the video and audio capture for my video recorder:

 for device in AVCaptureDevice.devices()
 {
     if (device as AnyObject).hasMediaType( AVMediaTypeAudio )
     {
         self.audioCapture = device as? AVCaptureDevice
     }
     else if (device as AnyObject).hasMediaType( AVMediaTypeVideo )
     {
         if (device as AnyObject).position == AVCaptureDevicePosition.back
         {
             self.backCameraVideoCapture = device as? AVCaptureDevice
         }
         else
         {
             self.frontCameraVideoCapture = device as? AVCaptureDevice
         }
     }
 }

When iOS 10 finally came out, I received the following warning when I was running my code. Note that my video recorder was still working smoothly for about 2 weeks.

'devices()' was deprecated in iOS 10.0: Use AVCaptureDeviceDiscoverySession instead.

As I was running my code this morning, my video recorder stopped working. xCode8 does not give me any errors but the previewLayer for the camera capture is completely white. When I then start recording I receive the following error:

Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" UserInfo={NSLocalizedDescription=The operation could not be completed, NSUnderlyingError=0x17554440 {Error Domain=NSOSStatusErrorDomain Code=-12780 "(null)"}, NSLocalizedFailureReason=An unknown error occurred (-12780)}

I believe that has something to do with the fact that I am using the deprecated approach AVCaptureDevice.devices() . Hence, I was wondering how to use AVCaptureDeviceDiscoverySession instead?

Thank you for your help in advance!

Answer 1

You can get the front camera with the following:

AVCaptureDevice.default(.builtInWideAngleCamera, for: AVMediaType.video, position: .front)

The back camera:

AVCaptureDevice.default(.builtInWideAngleCamera, for: AVMediaType.video, position: .back)

And the microphone:

AVCaptureDevice.default(.builtInMicrophone, for: AVMediaType.audio, position: .unspecified)

Answer 2

Here's my code (Swift 3) to get camera position :

// Find a camera with the specified AVCaptureDevicePosition, returning nil if one is not found
func cameraWithPosition(_ position: AVCaptureDevicePosition) -> AVCaptureDevice?
{
    if let deviceDescoverySession = AVCaptureDeviceDiscoverySession.init(deviceTypes: [AVCaptureDeviceType.builtInWideAngleCamera],
                                                          mediaType: AVMediaTypeVideo,
                                                          position: AVCaptureDevicePosition.unspecified) {

        for device in deviceDescoverySession.devices {
            if device.position == position {
                return device
            }
        }
    }

    return nil
}

If you want, you can also get the new devicesTypes from iPhone 7+ (dual camera) by changing the deviceTypes array.

Here's a good read : https://forums.developer.apple.com/thread/63347

Answer 3

Swift 4, iOS 10+ and Xcode 10.1 replaces

if let cameraID = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .front)?.localizedName {
       //cameraID = "Front Camera"
}

with AVCaptureDevice.DiscoverySession implementation

if let cameraID = AVCaptureDevice.DiscoverySession.init(deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera], mediaType: .video, position: .front).devices.first?.localizedName{
        //cameraID = "Front Camera"
} 

Need to wrap it with #available(iOS 10,*) check.

Answer 4

It works on Xcode 9.2 and Swift 4

AVCaptureDevice.default(.builtInWideAngleCamera, for: AVMediaType.video, position: .back)

https://developer.apple.com/documentation/avfoundation/avcapturedevice/2361508-default

Answer 5

Swift 3

For selecting the back camera:(also you can change .back as needed)

For selecting another deviceType simple add it inside the [ ] (ie:

[deviceTypeCamera, AVCaptureDeviceType.builtInMicrophone]

(or create a private let... like I did in the code with the back camera)

 private let position = AVCaptureDevicePosition.back
 private let deviceTypeBackCamera = AVCaptureDeviceType.builtInWideAngleCamera

 private func selectCaptureDevice() -> AVCaptureDevice? {
    return AVCaptureDeviceDiscoverySession(deviceTypes: [deviceTypeBackCamera], mediaType: AVMediaTypeVideo, position: position).devices.first

 }

Answer 6

example: iOS 11 Swift 4

override func viewDidLoad() {
    super.viewDidLoad()

    // Get the back-facing camera for capturing videos

    // AVCaptureDevice.default(.builtInWideAngleCamera, for: AVMediaType.video, position: .back)
    let deviceDiscoverySession = AVCaptureDevice.default(.builtInWideAngleCamera, for: AVMediaType.video, position: .back)

   guard let captureDevice = deviceDiscoverySession else {
       print("Failed to get the camera device")
       return
   }

    do {
        // Get an instance of the AVCaptureDeviceInput class using the previous device object.
        let input = try AVCaptureDeviceInput(device: captureDevice)

        // Set the input device on the capture session.
        captureSession.addInput(input)

    } catch {
        // If any error occurs, simply print it out and don't continue any more.
        print(error)
        return
    }

    // Initialize the video preview layer and add it as a sublayer to the viewPreview view's layer.
    videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    videoPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
    videoPreviewLayer?.frame = view.layer.bounds
    view.layer.addSublayer(videoPreviewLayer!)

    // Start video capture.
    captureSession.startRunning()

Answer 7

Try below code to get camera ID:

NSString *cameraID = nil;

NSArray *captureDeviceType = @[AVCaptureDeviceTypeBuiltInWideAngleCamera];
AVCaptureDeviceDiscoverySession *captureDevice = 
              [AVCaptureDeviceDiscoverySession 
                discoverySessionWithDeviceTypes:captureDeviceType 
                mediaType:AVMediaTypeVideo 
                position:AVCaptureDevicePositionUnspecified];

cameraID = [captureDevice.devices.lastObject localizedName];

Answer 8

For my video capture app I'm using the following code to get the mic, front and rear camera and I've tested this code from iOS 7 to 10.0.2.

        var frontCamera : AVCaptureDevice?
        var rearCamera : AVCaptureDevice?

        captureSession = AVCaptureSession()

        let devices = AVCaptureDevice.devicesWithMediaType(AVMediaTypeVideo)

        let audioDevices = AVCaptureDevice.devicesWithMediaType(AVMediaTypeAudio)

        for mic in audioDevices {
            audioDevice = mic as? AVCaptureDevice
            audioCapturePossible = true
        }

        for device in devices {
            if device.position == AVCaptureDevicePosition.Front {
                frontCamera = device as? AVCaptureDevice
                hasFrontCamera = true
            }
            else if device.position == AVCaptureDevicePosition.Back {
                rearCamera = device as? AVCaptureDevice
                hasRearCamera = true
            }

        }

Answer 9

Swift 4 (xCode 10.1)

This is what worked for me in the latest version of Swift. I did not see this answer, and it took me a while to suss out so here is how to get the front facing camera.

 if let device = AVCaptureDevice.defaultDevice(withDeviceType: .builtInWideAngleCamera , mediaType: AVMediaTypeVideo, position: .front)  {
    //Do the camera thing here..
}

Answer 10

Simplified:

func getCamera(with position: AVCaptureDevice.Position) -> AVCaptureDevice? {
    let deviceDescoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInDualCamera], mediaType: .video, position: .unspecified)
    return deviceDescoverySession.devices.first(where: { $0.position == position })
}

// and you can use like that:

guard let device = getCamera(with: .back) else { return }

Answer 11

在 Swift 5 中更容易

AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: AVMediaType.video, position: .front)

Answer 12

05/2019 :

 //video
        self.session = AVCaptureSession()
        guard
            let videoDeviceInput = try? AVCaptureDeviceInput(device: device!),
            self.session!.canAddInput(videoDeviceInput)
            else { return }
        self.session!.addInput(videoDeviceInput)

  //audio
        guard
            let audioDeviceInput = try? AVCaptureDeviceInput(device: mic!),
            self.session!.canAddInput(audioDeviceInput)
            else { return }
        self.session!.addInput(audioDeviceInput)