iot/projects/Demo/Demo.iOS/Controls/UICameraPreview.cs

using AVFoundation;
using CoreFoundation;
using CoreGraphics;
using CoreVideo;
using Demo.Controls;
using Foundation;
using System;
using System.Linq;
using UIKit;

namespace Demo.iOS.Controls
{
    public class UICameraPreview : UIView
    {
        private AVCaptureVideoPreviewLayer previewLayer;
        private CameraOptions cameraOptions;

        public AVCaptureSession CaptureSession { get; private set; }

        public bool IsPreviewing { get; set; }

        public UICameraPreview(CameraOptions options)
        {
            cameraOptions = options;
            IsPreviewing = false;
            Initialize();
        }

        public override void Draw(CGRect rect)
        {
            base.Draw(rect);
            previewLayer.Frame = rect;
        }

        private void Initialize()
        {
            CaptureSession = new AVCaptureSession();
            previewLayer = new AVCaptureVideoPreviewLayer(CaptureSession)
            {
                Frame = Bounds,
                VideoGravity = AVLayerVideoGravity.ResizeAspectFill
            };

            var videoDevices = AVCaptureDevice.DevicesWithMediaType(AVMediaType.Video);
            var cameraPosition = (cameraOptions == CameraOptions.Front) ? AVCaptureDevicePosition.Front : AVCaptureDevicePosition.Back;
            var device = videoDevices.FirstOrDefault(d => d.Position == cameraPosition);

            if (device == null)
            {
                return;
            }
            NSError error;
            var input = new AVCaptureDeviceInput(device, out error);
            CaptureSession.AddInput(input);

            //
            var output = new AVCaptureVideoDataOutput();//CVPixelFormatType.CV32BGRA
            output.WeakVideoSettings = new CVPixelBufferAttributes { PixelFormatType = CVPixelFormatType.CV32BGRA }.Dictionary;
            output.SetSampleBufferDelegateQueue(new SampleBufferDelegate(), new DispatchQueue("myQueue"));
            CaptureSession.AddOutput(output);
            //

            Layer.AddSublayer(previewLayer);
            CaptureSession.StartRunning();
            IsPreviewing = true;
        }
    }
}