Vision+Extensions.swift

import Vision

extension VNClassificationObservation {
    var debugString: String {
    """
        Confidence: \(String(format: "%.f", confidence * 100))%
        Guesses: \(identifier)
"""
    }
}

extension VNRequest {
    static func fromFile(named name: String,
                         withExtension extension: String = "mlmodelc",
                         completion: @escaping (String) -> Void) -> VNRequest {
        
        guard let modelURL = Bundle.main.url(forResource: name, withExtension: "mlmodelc") else {
            fatalError("Model file is missing")
        }
        do {
            let visionModel = try VNCoreMLModel(for: MLModel(contentsOf: modelURL))
            return VNCoreMLRequest(model: visionModel) { (request, error) in
                DispatchQueue.main.async {
                    if let results = request.results {
                        guard let topLabelObservation = results.first as?
                                VNClassificationObservation else {
                            return
                        }
                        completion(topLabelObservation.debugString)
                    }
                }
            }
        } catch {
            fatalError(String(describing: error))
        }
    }
}