xcode中的自定义相机，Swift 3

Question

因此，我有一个问题，我试图创建一个自定义相机的Xcode，但是，由于某种原因，我无法得到它，以便它是设置为使用前面的相机。不管我在代码中做了什么修改，它似乎只使用后面的摄像头，我希望有人能慷慨地看一下下面的代码，看看我是不是遗漏了什么东西，或者哪里出了问题。任何帮助都将是非常感谢的，谢谢您的时间。

func SelectInputDevice() {

let devices = AVCaptureDevice.defaultDevice(withDeviceType: .builtInWideAngleCamera, 
              mediaType: AVMediaTypeVideo, position: .front)
 if devices?.position == AVCaptureDevicePosition.front {

 print(devices?.position)
 frontCamera = devices

}

currentCameraDevice = frontCamera
do {

   let captureDeviceInput = try AVCaptureDeviceInput(device: currentCameraDevice)
   captureSession.addInput(captureDeviceInput)

 } catch {

    print(error.localizedDescription)

  }

}

这就是frontCamera和currentCameraDevice是AVCaptureDevice的地方。

Answer 1

似乎您的代码中缺少了一些东西：

1)为了更改输入设备，需要在添加新设备并以session.beginConfiguration()结束之前通过调用session.commitConfiguration()重新配置会话。此外，应该对后台队列进行所有更改(希望您已经为会话创建了该队列)，以便在配置会话时不会阻止UI。

2)在使用session.canAddInput(captureDeviceInput) +删除以前的设备(后摄像头)添加新设备之前，使用front+back配置是不允许的，因此与会话检查比较安全。

3)还会更干净地检查你的设备是否有一个工作前摄像头(可能是坏的)之前，以防止任何碰撞。

将捕获设备改为前置摄像机的完整代码如下：

func switchCameraToFront() {

    //session & sessionQueue are references to the capture session and its dispatch queue 
    sessionQueue.async { [unowned self] in

        let currentVideoInput = self.videoDeviceInput //ref to current videoInput as setup in initial session config

        let preferredPosition: AVCaptureDevicePosition = .front
        let preferredDeviceType: AVCaptureDeviceType = .builtInWideAngleCamera

        let devices = self.videoDeviceDiscoverySession.devices!
        var newVideoDevice: AVCaptureDevice? = nil

        // First, look for a device with both the preferred position and device type. Otherwise, look for a device with only the preferred position.
        if let device = devices.filter({ $0.position == preferredPosition && $0.deviceType == preferredDeviceType }).first {
            newVideoDevice = device
        }
        else if let device = devices.filter({ $0.position == preferredPosition }).first {
            newVideoDevice = device
        }

        if let videoDevice = newVideoDevice {
            do {
                let videoDeviceInput = try AVCaptureDeviceInput(device: videoDevice)

                self.session.beginConfiguration()

                // Remove the existing device input first, since using the front and back camera simultaneously is not supported.
                self.session.removeInput(currentVideoInput)

                if self.session.canAddInput(videoDeviceInput) {                                              

                    self.session.addInput(videoDeviceInput)
                    self.videoDeviceInput = videoDeviceInput
                }
                else {
                    //fallback to current device
                    self.session.addInput(self.videoDeviceInput);
                }
                self.session.commitConfiguration()
            }
            catch {

            }
        }
    }
}