swift中的音频播放器没有获得音量和音高的价值

Question

我正在尝试在 SwiftUI 中制作音频播放器，音频播放器应该具有这些功能。

1. 播放/停止音频
2. 循环播放
3. 通过滑块更改音量
4. 通过滑块更改音频音高。

目前我面临两个问题

1. 音频播放器未使用音量和音高滑块值
2. 当我停止并播放和更改音量/音高滑块时，应用程序崩溃并显示以下消息。

2020-10-14 17:34:08.957709+0530 SwiftUIAudioPlayer[1369:24886] [avae] AVAEInternal.h:109 [AVAudioFile.mm:484:-[AVAudioFile readIntoBuffer:frameCount:error:]: (ExtAudioFileRead(_imp->_extAudioFile, &ioFrames, buffer.mutableAudioBufferList)): 错误 -50

这是项目的链接。 https://github.com/varun-naharia/SwiftUIAudioPlayer

ContentView.swift

import Foundation
import SwiftUI

struct ContentView: View {
    @State var volume:Double = 0.00
    @State var pitch:Double = 0.0
    @State var musicFiles:[SoundModel] = [SoundModel(file: "metro35", name: "Metronome", fileExtension: "wav"), SoundModel(file: "johnson_tone_down_5min", name: "Johnson", fileExtension: "wav"), SoundModel(file: "sine_140_6s_fade_ogg", name: "Sine wave", fileExtension: "wav")]
    @State var selectedMusicFile:SoundModel = SoundModel(file: "sine_140_6s_fade_ogg", name: "Sine wave", fileExtension: "wav")
    @State var showSoundPicker = false
    @State var selectedGraph = "skin_conductance"
    @State var iconSize:CGFloat = 0.124
    @State var iconSpace:CGFloat = 0.015
    @State var heart = false
    
    init() {
        Player.setPitch(pitch: Float(self.pitch))
        Player.setVolume(volume: Float(self.volume))
    }
    
    var body: some View {
        GeometryReader { geometry in
            ZStack{
                VStack(alignment: .leading) {
                    Button(action: {
                        self.heart = !self.heart
                        self.selectedGraph = "heart"
                        if(self.heart)
                        {
                            Player.playMusic(musicfile: self.selectedMusicFile.file, fileExtension: self.selectedMusicFile.fileExtension)
                        }
                        else
                        {
                            Player.stopMusic()
                            self.selectedGraph = ""
                        }
                    })
                    {
                        
                        Image(self.selectedGraph == "heart" ? "heart" : "heart_disabled")
                            .resizable()
                            .frame(width: geometry.size.height*self.iconSize, height: geometry.size.height*self.iconSize)
                        
                    }
                    .frame(width: geometry.size.height*self.iconSize, height: geometry.size.height*self.iconSize)
                    .padding(.bottom, geometry.size.height*(self.iconSpace/2))
                    
                    Button(action: {
                        self.showSoundPicker = !self.showSoundPicker
                    })
                    {
                        
                        Image("tone")
                            .resizable()
                            .frame(width: geometry.size.height*self.iconSize, height: geometry.size.height*self.iconSize)
                        
                    }
                    .frame(width: geometry.size.height*self.iconSize, height: geometry.size.height*self.iconSize)
                    .padding(.bottom, geometry.size.height*(self.iconSpace/2))
                    
                    HStack{
                        SwiftUISlider(
                            thumbColor: .green,
                            thumbImage: "musicNote 2",
                            value: self.$volume
                        ).padding(.horizontal)
                        Button(action: {
                            
                        })
                        {
                            
                            Image("centerGraph")
                                .resizable()
                                .frame(width: geometry.size.width*0.05, height: geometry.size.width*0.05)
                            
                            
                        }
                        .frame(width: geometry.size.width*0.03, height: geometry.size.width*0.03)
                        SwiftUISlider(
                            thumbColor: .green,
                            
                            thumbImage: "timerSlider 2",
                            minValue: 0,
                            maxValue: 20,
                            value: self.$pitch
                            
                        )
                            .padding(.horizontal)
                            .frame(width: (geometry.size.width/2)-geometry.size.width*0.05, height: geometry.size.width*0.05)
                    }
                    .background(Color(UIColor.lightGray))
                    .frame(width: geometry.size.width, height: geometry.size.height*0.10)
                    if(self.showSoundPicker)
                    {
                        ChooseSoundView(
                            musicFiles: self.musicFiles,
                            selectedMusicFile: self.$selectedMusicFile ,
                            showSoundPicker: self.$showSoundPicker,
                            isPlaying: self.selectedGraph != ""
                        )
                            .frame(width: geometry.size.width*0.6, height: geometry.size.height*0.7, alignment: .center)
                            .background(Color.white)
                    }
                        
                }
                .frame(maxWidth: geometry.size.width,
                       maxHeight: geometry.size.height)
                .background(Color(UIColor.lightGray))
                
            }
        }
    }
}

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



struct ChooseSoundView: View {
    @State var musicFiles:[SoundModel]
    @Binding var selectedMusicFile:SoundModel
    @Binding var showSoundPicker:Bool
    @State var isPlaying:Bool
    var body: some View {
        GeometryReader { geometry in
            VStack(alignment: .leading)
            {
                List(self.musicFiles, id: \.name)
                { item in
                    Image(self.selectedMusicFile.file == item.file ? "radio-button_on" : "radio-button_off")
                        .resizable()
                        .frame(width: 15, height: 15)
                    Button(action: {
                        print(item.name)
                        self.selectedMusicFile = item
                        self.showSoundPicker = false
                        if(self.isPlaying)
                        {
                            //                            Player.stopMusic()
                            //                            Player.playMusic(musicfile: self.selectedMusicFile.file, fileExtension: self.selectedMusicFile.fileExtension)
                        }
                    }){
                        Text(item.name)
                            .frame(width: geometry.size.width*90,
                                   height: 50.0,
                                   alignment: .leading)
                    }
                    .frame(width: geometry.size.width*90, height: 50.0)
                }
                HStack{
                    Button(action: {
                        self.showSoundPicker = false
                    }){
                        Text("Done")
                            .frame(width: geometry.size.width*0.45,
                                   height: 50.0,
                                   alignment: .center)
                    }
                    .frame(width: geometry.size.width*0.45, height: 50.0)
                    Button(action: {
                        self.showSoundPicker = false
                    }){
                        Text("Cancel")
                            .frame(width: geometry.size.width*0.45,
                                   height: 50.0,
                                   alignment: .center)
                    }
                    .frame(width: geometry.size.width*0.45, height: 50.0)
                }
                .background(Color.white)
            }
        }
    }
}

Player.swift

import Foundation
import AVFoundation

class Player {
    
    private static var breathAudioPlayer:AVAudioPlayer?
    private static var audioPlayerEngine = AVAudioEngine()
    private static let speedControl = AVAudioUnitVarispeed()
    private static var pitchControl = AVAudioUnitTimePitch()
    private static var audioPlayerNode = AVAudioPlayerNode()
    private static var volume:Float = 1.0
    private static func playSounds(soundfile: String) {
    
    
        if let path = Bundle.main.path(forResource: soundfile, ofType: "m4a"){
            
            do{
                
                breathAudioPlayer = try AVAudioPlayer(contentsOf: URL(fileURLWithPath: path))
                breathAudioPlayer?.volume = self.volume
                breathAudioPlayer?.prepareToPlay()
                breathAudioPlayer?.play()
                
            }catch {
                print("Error")
            }
        }
    }
    
    static func playMusic(musicfile: String, fileExtension:String) {
        if let path = Bundle.main.path(forResource: musicfile, ofType: fileExtension){
            
            do{
                // 1: load the file
                let audioPlayFile = try AVAudioFile(forReading: URL(fileURLWithPath: path))
                let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: audioPlayFile.fileFormat, frameCapacity: AVAudioFrameCount(audioPlayFile.length))
                try? audioPlayFile.read(into: audioFileBuffer!)
                
                // 2: create the audio player
                
                audioPlayerNode = AVAudioPlayerNode()
                
                audioPlayerEngine = AVAudioEngine()
                
                // you can replace mp3 with anything else you like, just make sure you load it from our project
                
                // making sure to clean up the audio hardware to avoid any damage and bugs
                
                audioPlayerNode.stop()
                
                audioPlayerEngine.stop()
                
                audioPlayerEngine.reset()
                
                audioPlayerEngine.attach(audioPlayerNode)
                
                let pitchControl = AVAudioUnitTimePitch()
                
                // assign the speed and pitch
                
                audioPlayerEngine.attach(pitchControl)
                
                audioPlayerEngine.connect(audioPlayerNode, to: pitchControl, format: nil)
                
                audioPlayerEngine.connect(pitchControl, to: audioPlayerEngine.outputNode, format: nil)
                
                audioPlayerNode.scheduleFile(audioPlayFile, at: nil, completionHandler: nil)
                
                // try to start playing the audio
                audioPlayerNode.scheduleBuffer(audioFileBuffer!, at: nil, options: .loops, completionHandler: nil)
                do {
                    try audioPlayerEngine.start()
                } catch {
                    print(error)
                }
                
                // play the audio
                
                
                
                audioPlayerNode.play()
            }catch {
                print("Error")
            }
        }
    }
    static func breathIn() {
//            Player.playSounds(soundfile: "breathin")
    }
    
    static func breathOut() {
//            Player.playSounds(soundfile: "breathout")
    }
    
    static func play(musicFile:String, fileExtension:String)
    {
        
        Player.playMusic(musicfile: musicFile,fileExtension: fileExtension)
        
    }
    
    static func stopMusic() {
        audioPlayerNode.pause()
        audioPlayerNode.stop()
    }
    
    static func setPitch(pitch:Float) {
        pitchControl.pitch = pitch
    }
    
    static func setVolume(volume:Float) {
        audioPlayerNode.volume = volume
    }
}

SwiftUISlider.swift

import Foundation
import SwiftUI

struct SwiftUISlider: UIViewRepresentable {
    var onChangeNotification:String = ""
    
    final class Coordinator: NSObject {
        // The class property value is a binding: It’s a reference to the SwiftUISlider
        // value, which receives a reference to a @State variable value in ContentView.
        var value: Binding<Double>
        
        // Create the binding when you initialize the Coordinator
        init(value: Binding<Double>) {
            self.value = value
        }
        
        // Create a valueChanged(_:) action
        @objc func valueChanged(_ sender: UISlider) {
            self.value.wrappedValue = Double(sender.value)
            
        }
    }
    
    var thumbColor: UIColor = .white
    var minTrackColor: UIColor?
    var maxTrackColor: UIColor?
    var thumbImage:String?
    var minValue:Float?
    var maxValue:Float?
    
    @Binding var value: Double
    
    func makeUIView(context: Context) -> UISlider {
        let slider = UISlider(frame: .zero)
        slider.thumbTintColor = thumbColor
        slider.minimumTrackTintColor = minTrackColor
        slider.maximumTrackTintColor = maxTrackColor
        slider.value = Float(value)
        if(self.minValue != nil)
        {
            slider.minimumValue = self.minValue!
        }
        if(self.maxValue != nil)
        {
            slider.maximumValue = self.maxValue!
        }
        slider.setThumbImage(UIImage(named: self.thumbImage ?? ""), for: .normal)
        slider.setThumbImage(UIImage(named: self.thumbImage ?? ""), for: .focused)
        slider.setThumbImage(UIImage(named: self.thumbImage ?? ""), for: .highlighted)
        
        slider.addTarget(
            context.coordinator,
            action: #selector(Coordinator.valueChanged(_:)),
            for: .valueChanged
        )
        
        return slider
    }
    
    func onValueChange(_ sender: UISlider) {
        
    }
    
    func updateUIView(_ uiView: UISlider, context: Context) {
        // Coordinating data between UIView and SwiftUI view
        uiView.value = Float(self.value)
    }
    
    func makeCoordinator() -> SwiftUISlider.Coordinator {
        Coordinator(value: $value)
    }
}

SoundModel.swift

import Foundation
import Combine

class SoundModel:ObservableObject, Identifiable
{
    @Published var file:String
    @Published var name:String
    @Published var fileExtension:String
    
    init(file:String, name:String, fileExtension:String) {
        self.file = file
        self.name = name
        self.fileExtension = fileExtension
    }
}

Answer 1

您的第一个问题是您没有跟踪音量/音高值的变化。为此，将它们移动到一个类中：

class PlayerSetup: ObservableObject {
    @Published var volume:Double = 0.00 {
        didSet {
            Player.setVolume(volume: Float(self.volume))
        }
    }
    @Published var pitch:Double = 0.0{
        didSet {
            Player.setPitch(pitch: Float(self.pitch))
        }
    }
}

在视图中声明：

@ObservedObject var playerSetup = PlayerSetup()

并绑定到您的视图：

SwiftUISlider(
    thumbColor: .green,
    thumbImage: "musicNote 2",
    value: $playerSetup.volume
).padding(.horizontal)
SwiftUISlider(
    thumbColor: .green,
    
    thumbImage: "timerSlider 2",
    minValue: 0,
    maxValue: 20,
    value: $playerSetup.pitch
    
)

播放完文件时它会崩溃，因为try? audioPlayFile.read(into: audioFileBuffer!) 失败并且您的缓冲区安排在文件为空之后。由于scheduleFile，它第一次播放该文件。如果您想循环单个文件，请尝试调用此函数：

static func scheduleNext(audioPlayFile: AVAudioFile) {
    audioPlayerNode.scheduleFile(audioPlayFile, at: nil) {
        DispatchQueue.main.async {
            scheduleNext(audioPlayFile: audioPlayFile)
        }
    }
}

pitchControl 不起作用，因为您在开始播放时使用的是本地值，只需删除本地值声明即可。

关于音量。正如你在文档中看到的那样，This property is implemented only by the AVAudioEnvironmentNode and AVAudioMixerNode class mixers. 所以你不能将它用于播放器节点，你需要创建一个混音器节点，将其添加到节点链中，并更改它的音量。

另外为了清理节点代码，我建议你使用以下代码：

let nodes = [
    audioPlayerNode,
    pitchControl,
    mixerNode,
]
nodes.forEach { node in
    audioPlayerEngine.attach(node)
}
zip(nodes, (nodes.dropFirst() + [audioPlayerEngine.outputNode]))
    .forEach { firstNode, secondNode in
        audioPlayerEngine.connect(firstNode, to: secondNode, format: nil)
    }

它将所有nodes一一连接。

https://github.com/PhilipDukhov/SwiftUIAudioPlayer/tree/fixes

Answer 2

您的代码的主要问题是它们之间存在混合视图和视图模型。很多东西现在必须在 viewModel 中，位于 View 中。

查看：

struct ContentView: View {
    @State var volume:Double = 0.00
    @State var pitch:Double = 0.0
    @State var musicFiles:[SoundModel] = [SoundModel(file: "metro35", name: "Metronome", fileExtension: "wav"), SoundModel(file: "johnson_tone_down_5min", name: "Johnson", fileExtension: "wav"), SoundModel(file: "sine_140_6s_fade_ogg", name: "Sine wave", fileExtension: "wav")]
    @State var selectedMusicFile:SoundModel = SoundModel(file: "sine_140_6s_fade_ogg", name: "Sine wave", fileExtension: "wav")
    @State var showSoundPicker = false
    @State var selectedGraph = "skin_conductance"
    @State var iconSize:CGFloat = 0.124
    @State var iconSpace:CGFloat = 0.015
    @State var heart = false
    
    init() {
        Player.setPitch(pitch: Float(self.pitch))
        Player.setVolume(volume: Float(self.volume))
    }

视图必须是：

struct PlayerView: View {
    @ObservedObject var viewModel: PlayerViewModel
    @State var iconSize:CGFloat = 0.124
    @State var iconSpace:CGFloat = 0.015
    
    init() {
    // that was wrote here must be moved to init of playerViewModel
    }
    

查看您的模型：

import Foundation
import AVFoundation

class Player {
    
    private static var breathAudioPlayer:AVAudioPlayer?
    private static var audioPlayerEngine = AVAudioEngine()
    private static let speedControl = AVAudioUnitVarispeed()
    private static var pitchControl = AVAudioUnitTimePitch()
    private static var audioPlayerNode = AVAudioPlayerNode()
    private static var volume:Float = 1.0
    private static func playSounds(soundfile: String) {
    ....

ViewModel 必须是：

import Foundation
import AVFoundation

class PlayerViewModel: ObservableObject {
    @Published var volume:Double = 0.00
    @Published var pitch:Double = 0.0
    @Published var musicFiles:[SoundModel] = [SoundModel(file: "metro35", name: "Metronome", fileExtension: "wav"), SoundModel(file: "johnson_tone_down_5min", name: "Johnson", fileExtension: "wav"), SoundModel(file: "sine_140_6s_fade_ogg", name: "Sine wave", fileExtension: "wav")]
    @Published var selectedMusicFile:SoundModel = SoundModel(file: "sine_140_6s_fade_ogg", name: "Sine wave", fileExtension: "wav")
    @Published var showSoundPicker = false
    @Published var selectedGraph = "skin_conductance"

    //@Published var heart = false // SoundViewModel's property

    private static var breathAudioPlayer:AVAudioPlayer?
    private static var audioPlayerEngine = AVAudioEngine()
    private static let speedControl = AVAudioUnitVarispeed()
    private static var pitchControl = AVAudioUnitTimePitch()
    private static var audioPlayerNode = AVAudioPlayerNode()
    private static var volume:Float = 1.0
    private static func playSounds(soundfile: String) {
    

如果您将所有这些都移到适当的位置，几乎可以肯定您的代码会更好地工作，并且您的问题可能会得到解决。

目前您需要手动跟踪任何更改。你的代码结构是这个原因。您不需要手动跟踪它，因为这是额外的无用代码。 您需要修复代码结构而不是使用“didSet”