Swift Solid Metronome System

Question

I am trying to build a reliable solid system to build a metronome in my app using SWIFT.

I Have built what seems to be a solid system using NSTimer so far.. The only

Answer 1

Ok! You can't get things right basing on time, because somehow we need to deal with DA converters and their frequency - samplerate. We need to tell them the exact sample to start play the sound. Add a single view iOS app with two buttons start and stop and insert this code into ViewController.swift. I keep things simple and it's just an Idea of how we can do this. Sorry for forcing try... This one is made with swift 3. Also check out my project on GitHub https://github.com/AlexShubin/MetronomeIdea

Swift 3

   import UIKit
    import AVFoundation

    class Metronome {

        var audioPlayerNode:AVAudioPlayerNode
        var audioFile:AVAudioFile
        var audioEngine:AVAudioEngine

        init (fileURL: URL) {

            audioFile = try! AVAudioFile(forReading: fileURL)

            audioPlayerNode = AVAudioPlayerNode()

            audioEngine = AVAudioEngine()
            audioEngine.attach(self.audioPlayerNode)

            audioEngine.connect(audioPlayerNode, to: audioEngine.mainMixerNode, format: audioFile.processingFormat)
            try! audioEngine.start()

        }

        func generateBuffer(forBpm bpm: Int) -> AVAudioPCMBuffer {
            audioFile.framePosition = 0
            let periodLength = AVAudioFrameCount(audioFile.processingFormat.sampleRate * 60 / Double(bpm))
            let buffer = AVAudioPCMBuffer(pcmFormat: audioFile.processingFormat, frameCapacity: periodLength)
            try! audioFile.read(into: buffer)
            buffer.frameLength = periodLength
            return buffer
        }

        func play(bpm: Int) {

            let buffer = generateBuffer(forBpm: bpm)

   self.audioPlayerNode.play()

            self.audioPlayerNode.scheduleBuffer(buffer, at: nil, options: .loops, completionHandler: nil)



        }

        func stop() {

            audioPlayerNode.stop()

        }

    }


    class ViewController: UIViewController {

        var metronome:Metronome

        required init?(coder aDecoder: NSCoder) {

            let fileUrl = Bundle.main.url(forResource: "Click", withExtension: "wav")

            metronome = Metronome(fileURL: fileUrl!)

            super.init(coder: aDecoder)

        }

        @IBAction func StartPlayback(_ sender: Any) {

            metronome.play(bpm: 120)

        }

        @IBAction func StopPlayback(_ sender: Any) {

            metronome.stop()

        }

    }