Looping audio test with AudioKit using Timer & CADisplayLink

gistfile1.txt

///This loops between two audio files that are two seconds long.
///The audio files are longer than two seconds to include the fade between files
///
///Using CADisplayLink
import AudioKit
import AVFoundation
import SwiftUI

class InstrumentEXSConductor: ObservableObject, HasAudioEngine {
    let engine = AudioEngine()
    let player1 = AudioPlayer()
    let player2 = AudioPlayer()
    var loopNumber = 1
    var _lastCallTime = NSDate()
    var _currentCallTime = NSDate()
    var firstPlayer = true
    var displayLink: CADisplayLink?
    init() {
        engine.output = Mixer(player1,player2)
        let link = CADisplayLink(target: self, selector: #selector(update))
        link.add(to: .main, forMode: .common)
        displayLink = link
        try! self.player2.load(url: (Bundle.main.resourceURL?.appendingPathComponent("Sounds/loop2.wav"))!,buffered: true)
        self.player2.play()
        try! self.player1.load(url: (Bundle.main.resourceURL?.appendingPathComponent("Sounds/loop1.wav"))!,buffered: true)
        self.player1.play()
        player1.stop()
        player2.stop()
    }
    
    @objc func update() {
        _currentCallTime = Date.now as NSDate
        let differenceInSeconds = Int(_currentCallTime.timeIntervalSince(_lastCallTime as Date))
        print(differenceInSeconds)
        if differenceInSeconds > 1 {
            self._lastCallTime = self._currentCallTime
                
            if self.firstPlayer {
                self.player1.stop()
                try! self.player1.load(url: (Bundle.main.resourceURL?.appendingPathComponent("Sounds/loop\(loopNumber).wav"))!,buffered: true)
                self.player1.play()
            } else {
                self.player2.stop()
                try! self.player2.load(url: (Bundle.main.resourceURL?.appendingPathComponent("Sounds/loop\(loopNumber).wav"))!,buffered: true)
                self.player2.play()
            }
            self.firstPlayer = !self.firstPlayer
        }
    }
}

struct InstrumentEXSView: View {
    @StateObject var conductor = InstrumentEXSConductor()
    @Environment(\.colorScheme) var colorScheme

    var body: some View {
        Button(action: {conductor.loopNumber = 1} , label: {
            Text("Loop1")
        })
        Button(action: {conductor.loopNumber = 2}, label: {
            Text("Loop2")
        }).cookbookNavBarTitle("Instrument EXS")
            .onAppear {
                conductor.start()
            }
            .onDisappear {
                conductor.stop()
                conductor.displayLink?.invalidate()
            }
    }
}

///Using Timer
/*
class InstrumentEXSConductor: ObservableObject, HasAudioEngine {
    let engine = AudioEngine()
    let player1 = AudioPlayer()
    let player2 = AudioPlayer()
    var loopNumber = 1
    var firstPlayer = true
    var timer = Timer()
    
    init() {
        engine.output = Mixer(player1,player2)
        timer = Timer.scheduledTimer(timeInterval: 2, target: self, selector: #selector(self.update), userInfo: nil, repeats: true)
        try! self.player2.load(url: (Bundle.main.resourceURL?.appendingPathComponent("Sounds/loop2.wav"))!,buffered: true)
        self.player2.play()
        try! self.player1.load(url: (Bundle.main.resourceURL?.appendingPathComponent("Sounds/loop1.wav"))!,buffered: true)
        self.player1.play()
        player1.stop()
        
        player2.stop()
    }
    
    @objc func update() {
        if self.firstPlayer {
            self.player1.stop()
            try! self.player1.load(url: (Bundle.main.resourceURL?.appendingPathComponent("Sounds/loop\(loopNumber).wav"))!,buffered: true)
            self.player1.play()
        } else {
            self.player2.stop()
            try! self.player2.load(url: (Bundle.main.resourceURL?.appendingPathComponent("Sounds/loop\(loopNumber).wav"))!,buffered: true)
            self.player2.play()
        }
        self.firstPlayer = !self.firstPlayer
    }
}

struct InstrumentEXSView: View {
    @StateObject var conductor = InstrumentEXSConductor()
    @Environment(\.colorScheme) var colorScheme
    
    var body: some View {
        Button(action: {conductor.loopNumber = 1} , label: {
            Text("Loop1")
        })
        Button(action: {conductor.loopNumber = 2}, label: {
            Text("Loop2")
        }).cookbookNavBarTitle("Instrument EXS")
            .onAppear {
                conductor.start()
            }
            .onDisappear {
                conductor.stop()
                conductor.timer.invalidate()
            }
    }
}
*/