如何将字符串数组从视图模型传递到 swiftUI 中播放歌曲

Posted 2023-02-23

【中文标题】如何将字符串数组从视图模型传递到 swiftUI 中播放歌曲

【英文标题】：How to pass array of string from to view model to play song in swiftUI

【发布时间】：2021-01-27 10:36:28

【问题描述】：

我创建了一个模型并添加了嵌套结构。根据结构详细信息之一创建了一个数组，我想从模型中检索详细信息以查看模型以播放音乐。

我想检索这个“aURL”字符串并将其插入到播放函数中以播放音乐。

class myViewModel: ObservableObject 
@Published var isPlaying = false
var player = AVAudioPlayer()

func play()
    do
        player = try AVAudioPlayer(contentsOf: Array[0] as URL )
        if player.isPlayingplayer.pause()
        elseplayer.play()
        isPlaying = player.isPlaying
        
    catchprint("error")

【参考方案1】：

将var feelSongs: [myModel.M.A] 设为静态 喜欢

static var feelSongs: [myModel.M.A] 

并像这样在视图模型中使用它

class MyViewModel: ObservableObject 
    @Published var isPlaying = false
    var player = AVAudioPlayer()
    var arrData = myModel.M.feelSongs
    func play(with url: URL?)
        guard let url = url else 
            return
        
        do
            player = try AVAudioPlayer(contentsOf: url )
            if player.isPlayingplayer.pause()
            elseplayer.play()
            isPlaying = player.isPlaying
            
        catchprint("error")
    

注意：类名和结构名以大写字母开头。

【讨论】：

感谢您的回复。但是 var arrData = myModel.feelSongs，在这一行中，即使我已将其更改为静态 var，它也没有检索 feelSongs 变量以查看模型。

它仍然不能与 static 关键字一起使用，但是当我只与 var 关键字（如（var arrData = myModel.feelSongs）一起使用时，它会出现但我得到“不能使用实例成员'myModel'在属性初始化器中；属性初始化器在“self”可用之前运行”

【参考方案2】：

你的结构嵌套在结构中很奇怪，反正我不知道你的想法。

请测试一下：

class MyModel: Codable 

    var feelSongs: [MyModel.M.A] = [
        MyModel.M.A.init(id: 1, afcontent: "Feeling Happy", aURL: "a1.mp3", isOn: true),
        MyModel.M.A.init(id: 2, afcontent: "Feeling Sad", aURL: "a2.mp3", isOn: true),
        MyModel.M.A.init(id: 3, afcontent: "Feeling Positive", aURL: "a3.mp3", isOn: true),
        MyModel.M.A.init(id: 4, afcontent: "Feeling Healthy", aURL: "a4.mp3", isOn: true)
    ]
    struct M: Codable
        var mURL: String
        var bgMusic : String
        var bgVol : Double

        struct A : Codable, Identifiable 
            var id : Int
            var afcontent : String
            var aURL : String
            var isOn : Bool
            
            
        
    



class MyViewModel: ObservableObject 
    @Published var isPlaying = false
    var player = AVAudioPlayer()

    var theModel = MyModel()
    
    **//ADDED THIS**
    var playNow = 0

    func play()

        if playNow >= theModel.feelSongs.count 
            return
        
        let url = theModel.feelSongs[playNow]
        guard let url = URL(string: url) else 
            return
        
        
        **//ADDED THIS**
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "playerDidFinishPlaying:", name: AVPlayerItemDidPlayToEndTimeNotification, object: item) 
        do 
            player = try AVAudioPlayer(contentsOf: url )
            if player.isPlayingplayer.pause()
            elseplayer.play()
            isPlaying = player.isPlaying

        
        catchprint("error")
    

    **//ADDED THIS**
    func playerDidFinishPlaying(note: NSNotification) 
        play()
    

//
struct ContentView: View 
    var mymodel = MyViewModel()
    
    var body: some View 
        //Text("3")
        List(mymodel.theModel.feelSongs)  song in
            Text(song.afcontent)                    
        
        .onAppear 
             mymodel.play()
        
    




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

【讨论】：

非常感谢您的回复。但是如何通过播放按钮而不是列表来播放歌曲。

我想让这首歌一个接一个地自动播放。用户无法选择播放哪一个

@binavol329 我编辑了答案，反正改标题，你的要求现在不一样了