Create custom catalogs at scale with ShazamKit

/*
See LICENSE folder for this sample’s licensing information.

Abstract:
The model that is responsible for matching against the catalog and update the SwiftUI Views.
*/

import ShazamKit
import AVFAudio

struct MatchResult {
    var title: String?
    var equation: Equation?
    var episode: Episode?
    var answerRange: ClosedRange<Int>?
    
    var hasContent: Bool {
        equation != nil || title != nil || answerRange != nil
    }
}

class Matcher: NSObject, ObservableObject, SHSessionDelegate {
    @Published var matchResult: MatchResult?
    
    private var session: SHSession!
    private let audioEngine = AVAudioEngine()
    private var matchingTask: Task<Void, Never>? = nil
    
    func match(catalog: SHCustomCatalog) throws {
        
        session = SHSession(catalog: catalog)
        session.delegate = self
        
        let audioFormat = AVAudioFormat(standardFormatWithSampleRate: audioEngine.inputNode.outputFormat(forBus: 0).sampleRate,
                                        channels: 1)
        audioEngine.inputNode.installTap(onBus: 0, bufferSize: 2048, format: audioFormat) { [weak session] buffer, audioTime in
            session?.matchStreamingBuffer(buffer, at: audioTime)
        }
        
        try AVAudioSession.sharedInstance().setCategory(.record)
        AVAudioSession.sharedInstance().requestRecordPermission { [weak self] success in
            guard success, let self = self else { return }
            
            Task.detached {
                try? self.audioEngine.start()
            }
        }
        
        Task { @MainActor in
            for await case .match(let match) in session.results {
                self.matchResult = match.matchResult
            }
        }
    }
}

extension SHMatch {

    var matchResult: MatchResult {
        mediaItems.reduce(into: MatchResult()) { result, mediaItem in
            result.title = result.title ?? mediaItem.title
            result.episode = result.episode ?? mediaItem.episode
            result.equation = result.equation ?? mediaItem.equation
            result.answerRange = result.answerRange ?? mediaItem.answerRange
        }
    }
}

// Restrict this media item to only describe the first 5 seconds

 let mediaItem = SHMediaItem(properties: [
            .title: "Title",
            .timeRanges:[0.0..<5.0]
        ])

 let timeRanges: [Range<TimeInterval>] = mediaItem.timeRanges

let parentCatalog = SHCustomCatalog()

parentCatalog.add(from: URL(fileURLWithPath: "/path/to/Episode1.shazamcatalog"))
parentCatalog.add(from: URL(fileURLWithPath: "/path/to/Episode2.shazamcatalog"))
parentCatalog.add(from: URL(fileURLWithPath: "/path/to/Episode3.shazamcatalog"))

func within(range: Range<Float>, for matchedMediaItem: SHMatchedMediaItem) -> Bool {
        
	range.contains(matchedMediaItem.frequencySkew)
}

// Restrict this media item to only describe the first 5 seconds

 let mediaItem = SHMediaItem(properties: [
            .title: “Frequency Skewed Audio”,
            .frequencySkewRanges:[0.01..<0.02]
        ])

 let frequencySkewRanges: [Range<Float>] = mediaItem.frequencySkewRanges