SwiftUIでAVAudioPlayerNodeで音楽を再生し、再生終了を検知する


SwiftUIでAVAudioPlayerNodeで音楽を再生し、再生終了を検知する方法です。 AVAudioPlayer は Delegate で再生終了を検知しますが、AVAudioPlayerNodeは再生終了時に呼ばれるハンドラーが用意されているのでそちらを使います。

参考: AVAudioEngine & AVAudioPlayerNode didFinish method like AVAudioPlayer

ContentView.swift

import SwiftUI
import AVFoundation

struct ContentView: View {
    @State var audioPlayerNode = AVAudioPlayerNode()
    @State var audioEngine = AVAudioEngine()
    @State var speedControl = AVAudioUnitVarispeed()
    @State var pitchControl = AVAudioUnitTimePitch()
    
    var body: some View {
        VStack {
            HStack {
                Button("Start") {
                    guard let url = Bundle.main.url(forResource: "melody", withExtension: "wav") else { return }
                    guard let file = try? AVAudioFile(forReading: url) else { return }
                    
                    audioPlayerNode = AVAudioPlayerNode()
                    
                    audioEngine.attach(audioPlayerNode)
                    audioEngine.attach(pitchControl)
                    audioEngine.attach(speedControl)
                    
                    audioEngine.connect(audioPlayerNode, to: speedControl, format: nil)
                    audioEngine.connect(speedControl, to: pitchControl, format: nil)
                    audioEngine.connect(pitchControl, to: audioEngine.mainMixerNode, format: nil)
                    audioPlayerNode.scheduleFile(file, at: nil) {
                        print("Did Finish")
                    }
                    try? audioEngine.start()
                    audioPlayerNode.play()
                }.padding()
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}
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