swift - 类型 AVCaptureDevice 不符合协议(protocol)序列

Question

我正在尝试打开前置摄像头以进行自拍并将其保存为输出静止图像，以便用户能够在提交前看到照片。我配置的原始功能在 iOS 10 中已贬值。有人可以帮助理解如何正确编写吗？

 //OLD CODE:
 let devices = AVCaptureDevice.devicesWithMediaType(AVMediaTypeVideo)
    for device in devices {

       if device.position == AVCaptureDevicePosition.Front {


            do {

                let input = try AVCaptureDeviceInput(device: device as! AVCaptureDevice)
                if captureSession.canAddInput(input) { ... 
 //NEW CODE:   
   let devices = AVCaptureDevice.default(.builtInWideAngleCamera, for: AVMediaType.video, position: .front)
     )

    for device in devices {
        if device.position == AVCaptureDevice.Position.front {

            do {
                let input = try AVCaptureDeviceInput(device: devices)
                if captureSession.canAddInput(input) {
                    captureSession.addInput(input)
                    stillImageOutput.outputSettings = [AVVideoCodecKey : AVVideoCodecJPEG]

                    if captureSession.canAddOutput(stillImageOutput) {
                        captureSession.add(stillImageOutput)
                        captureSession.startRunning()

                        previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
                        previewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill
                        previewLayer.connection?.videoOrientation = AVCaptureVideoOrientation.portrait
                        cameraView.layer.addSublayer(previewLayer)

                        previewLayer.bounds = cameraView.frame
                        previewLayer.position = CGPoint(x: cameraView.frame.width/2, y: cameraView.frame.height/2)

                    }
                }
            }
            catch {

            }
        }
    }

}

Answer 1

查看documentation

class func `default`(_ deviceType: AVCaptureDevice.DeviceType, 
                 for mediaType: AVMediaType?, 
            position: AVCaptureDevice.Position) -> AVCaptureDevice?

所以 default 方法返回一个可选的 AVCaptureDevice。

你只需要更换

//NEW CODE:   
   let devices = AVCaptureDevice.default(.builtInWideAngleCamera, for: AVMediaType.video, position: .front)
     )

    for device in devices {
        if device.position == AVCaptureDevice.Position.front {

与

//NEW CODE:   
        if let device = AVCaptureDevice.default(.builtInWideAngleCamera, for: AVMediaType.video, position: .front) {