Added method to request a specific camera unique identifier.

[dsmurfin]

No description provided.

[YuAo]

For #37, #38 and #41

I think the current form of the API is not suitable for these tasks.

For example:

• When user specifies both position and uniqueID, the position info is just ignored.
  Maybe we should use a enum here.

If we are going to add these features, we'd better redesign the related API.

[dsmurfin]

If we are going to add these features, we'd better redesign the related API.

I agree. I was attempting to resolve this feature in a way that did not break existing implementations.

An enum would be a better solution here. It might be desirable to provide a fallback option:

enum DeviceSelection {
   case .position(position: Position)
   case .device(uniqueID: String)
   case .device(uniqueID: String, format: AVCaptureDevice.Format)
   case .device(uniqueID: String, fallback: Position)
   case .device(uniqueID: String, format: AVCaptureDevice.Format, fallback: Position)
}

[YuAo]

It might be desirable to provide a fallback option.

This is a little confusing:

• Is the fallback option only used when the device with that uniqueID cannot be found? or the format is not supported or we have any error switching to that device?
• What if there's an error switching to the fallback device? Which error should we report: the error switching to the fallback device or the error switching to the requested device?

The no-fallback approach seems to be clearer and simpler. If there's an error switching to a requested device, we can catch that error and decide whether we should fallback to another device or directly present that error to our user.

---

How about this:

Just add a switchToVideoCaptureDevice(_ device: AVCaptureDevice) method.

If you don't care about a particular device you can still use switchToVideoCaptureDevice(with: AVCaptureDevice.Position, preferredDeviceTypes: [AVCaptureDevice.DeviceType]).

If you need to switch to a particular device you can use switchToVideoCaptureDevice(_ device: AVCaptureDevice). You can also set the active format after switching the device:

try camera.switchToVideoCaptureDevice(device)
try device.lockForConfiguration()
device.activeFormat = ...
device.unlockForConfiguration()

This maintains the simple interface for common use and exposes a way for capture device customization.

[dsmurfin]

Just add a switchToVideoCaptureDevice(_ device: AVCaptureDevice) method.

This makes more sense, it also removes the need for the preferredDeviceTypes which of course are not required in this context. The same principle could also be applied to audio instead of #38.

I am a bit tight for time over the next few days, but I will look to rework some of these PRs over the next week or so as per our discussions.

[YuAo]

I've implemented my proposal here #47. @dsmurfin Can you do a code review when you have time?

[dsmurfin]

Amazing, thanks! Yes, I will do that over the weekend if not before.