Custom camera in xcode, Swift 3 - swift

Question

So I have this issue where I am trying to create a custom camera in Xcode however, for some reason I cannot get it so that it is set to use the front camera. No matter what I change in the code it seems to only use the back camera and I was hoping that someone might be generous enough to take a quick look at my code below and see whether there is something that I am missing or somewhere that I went wrong. Any help would be very much appreciated, thank you for your time.
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)
}
}
This is where frontCamera and currentCameraDevice are a AVCaptureDevice's.

Answer 1

Seems there are a few things missing from your code:
1) In order to change input devices you need to reconfigure the session by calling session.beginConfiguration() before adding the new device and ending with session.commitConfiguration(). Also all changes should be made on the background queue (that hopefully you've created for the session) so that UI isn't blocked when session is configured.
2) Code would be safer to check with the session it allows the new device before adding it with session.canAddInput(captureDeviceInput) + removing the previous device (the back camera) as front+back config isn't allowed.
3) Also would be cleaner to check your device has a working front camera (might be broken) before to prevent any crashes.
Full code for changing capture device to front camera would look like:
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 {
}
}
}
}