xcode、Swift 中的自定义相机 3

Question

所以我遇到了这个问题，我试图在 Xcode 中创建一个自定义摄像头，但是由于某种原因我无法获取它，因此它被设置为使用前置摄像头。无论我在代码中更改什么，它似乎只使用后置摄像头，我希望有人能够慷慨地快速浏览一下我下面的代码，看看是否有我遗漏的东西或我去过的地方错误的。非常感谢您的帮助，感谢您的宝贵时间。

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)

  }

}

这里frontCamera和currentCameraDevice是一个AVCaptureDevice的。

Answer 1

您的代码中似乎缺少一些东西：

1) 为了更改输入设备，您需要在添加新设备并以 session.commitConfiguration() 结束之前调用 session.beginConfiguration() 来重新配置会话。此外，所有更改都应在后台队列（希望您已为会话创建）上进行，以便 UI 在配置会话时不会被阻止。

2) 在使用 session.canAddInput(captureDeviceInput) 添加新设备之前，检查允许新设备的会话代码会更安全 + 删除以前的设备（后置摄像头），因为不允许前后配置。

3) 在防止任何崩溃之前检查您的设备是否有一个工作的前置摄像头（可能坏了）也会更干净。

将捕获设备更改为前置摄像头的完整代码如下所示：

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({ [=10=].position == preferredPosition && [=10=].deviceType == preferredDeviceType }).first {
            newVideoDevice = device
        }
        else if let device = devices.filter({ [=10=].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 {

            }
        }
    }
}

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