AVCamBarcode.CameraViewController.ChangeCamera C# (CSharp) Метод

		void ChangeCamera ()
		{
			MetadataObjectTypesButton.Enabled = false;
			SessionPresetsButton.Enabled = false;
			CameraButton.Enabled = false;
			ZoomSlider.Enabled = false;

			// Remove the metadata overlay layers, if any.
			RemoveMetadataObjectOverlayLayers ();

			DispatchQueue.MainQueue.DispatchAsync (() => {
				var currentVideoDevice = videoDeviceInput.Device;
				var currentPosition = currentVideoDevice.Position;

				var preferredPosition = AVCaptureDevicePosition.Unspecified;

				switch (currentPosition) {
				case AVCaptureDevicePosition.Unspecified:
				case AVCaptureDevicePosition.Front:
					preferredPosition = AVCaptureDevicePosition.Back;
					break;

				case AVCaptureDevicePosition.Back:
					preferredPosition = AVCaptureDevicePosition.Front;
					break;
				}

				var videoDevice = DeviceWithMediaType (AVMediaType.Video, preferredPosition);
				if (videoDevice != null) {
					NSError err;
					var vDeviceInput = AVCaptureDeviceInput.FromDevice (videoDevice, out err);
					if (err != null) {
						Console.WriteLine ($"Error occured while creating video device input: {err}");
						return;
					}

					session.BeginConfiguration ();

					// Remove the existing device input first, since using the front and back camera simultaneously is not supported.
					session.RemoveInput (videoDeviceInput);

					// When changing devices, a session preset that may be supported
					// on one device may not be supported by another. To allow the
					// user to successfully switch devices, we must save the previous
					// session preset, set the default session preset (High), and
					// attempt to restore it after the new video device has been
					// added. For example, the 4K session preset is only supported
					// by the back device on the iPhone 6s and iPhone 6s Plus. As a
					// result, the session will not let us add a video device that
					// does not support the current session preset.
					var previousSessionPreset = session.SessionPreset;
					session.SessionPreset = AVCaptureSession.PresetHigh;

					if (session.CanAddInput (vDeviceInput)) {
						session.AddInput (vDeviceInput);
						videoDeviceInput = vDeviceInput;
					} else {
						session.AddInput (videoDeviceInput);
					}

					// Restore the previous session preset if we can.
					if (session.CanSetSessionPreset (previousSessionPreset))
						session.SessionPreset = previousSessionPreset;

					session.CommitConfiguration ();
				}

				MetadataObjectTypesButton.Enabled = true;
				SessionPresetsButton.Enabled = true;
				CameraButton.Enabled = true;
				ZoomSlider.Enabled = true;
				ZoomSlider.MaxValue = (float)NMath.Min (videoDeviceInput.Device.ActiveFormat.VideoMaxZoomFactor, 8);
				ZoomSlider.Value = (float)videoDeviceInput.Device.VideoZoomFactor;
			});
		}