VisionDataModel.swift

import SwiftUI
import AVFoundation.AVCaptureSession
import Vision.VNRequest

class DataModel: NSObject, ObservableObject, AVCaptureVideoDataOutputSampleBufferDelegate {
    static let shared = DataModel(debugString: "")
    @Published var session = AVCaptureSession()
    @Published var debugString = ""
    @Published var previewView = UIView(frame: CGRect(x: 0, y: 0, width: 375, height: 667))
    var requests = [VNRequest]()
    
    convenience init(debugString: String) {
        self.init()
        requests = [.fromFile(named: "MobileNet") { debugString in
            self.debugString = debugString }]
        session.setup(delegate: self)
        session.startRunning()
    }
    
    func captureOutput(_ output: AVCaptureOutput,
                       didOutput sampleBuffer: CMSampleBuffer,
                       from connection: AVCaptureConnection) {
        do {
            if let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) {
                try VNImageRequestHandler(
                    cvPixelBuffer: pixelBuffer,
                    orientation: .up,
                    options: [:])
                .perform(DataModel.shared.requests)
            }
        } catch {
            fatalError(error.localizedDescription)
        }
    }
}