ios - swift 2 : Can't find audio file path when I use variables as file names

Question

这是我正在努力解决的一个非常奇怪的现象:

我正在尝试根据特定上下文单击按钮来播放音频文件。例如，如果条件“A”，我将播放某种声音(单击按钮时)，如果是“B”，我将播放另一种声音。我使用 switch 语句来决定在哪种条件下播放什么声音。

问题:即使我得到了正常工作的条件，AVAudioPlayer 总是返回 nil。但是当我硬编码要播放的文件时，它工作得很好。只有当我使用变量来决定“在 switch 语句中”播放哪个声音时，声音才会不播放，否则当我使用静态变量而不更改其值时，它可以正常工作。

这是我的代码:

func playSound(Condition: String){

    switch Condition {
    case "1":
        soundName = "1"
    case "2":
        soundName = "2"
    case "3":
        soundName = "3"
    case "4":
        soundName = "4"
    case "5":
        soundName = "5"
    default:
        soundName = "default"
    }

  let pathString = NSBundle.mainBundle().URLForResource(soundName, withExtension: "m4a")?.path //if I type 'let soundName = "1" or Hard code the value' - it will work fine

    if let soundFilePath = pathString {
        let sound = NSURL.fileURLWithPath(soundFilePath)

        do{
            audioPlayer = try AVAudioPlayer(contentsOfURL:sound)
            audioPlayer.prepareToPlay()
            audioPlayer.play()
        }catch {
            print("Error getting the audio file")
        }
    } else {
        print("Error: Can't find file. Path is nil") // - This is always printed when I use the variable result from the switch
    }
}

谁能帮我找出原因吗？切换时间是否太长？我怀疑是因为我可以在播放声音之前打印条件的值。提前致谢。

在此处添加了更多信息:https://forums.developer.apple.com/message/137380#137380

Answer 1

您需要声明 soundName

即

func playSound(Condition: String){

var soundName: String

switch Condition {
case "1":
    soundName = "1"
case "2":
    soundName = "2"
case "3":
    soundName = "3"
case "4":
    soundName = "4"
case "5":
    soundName = "5"
default:
    soundName = "default"
}

let pathString = NSBundle.mainBundle().URLForResource(soundName, withExtension: "m4a")?.path//如果我输入 'let soundName = "1"或对值进行硬编码' - 它将正常工作

if let soundFilePath = pathString {
    let sound = NSURL.fileURLWithPath(soundFilePath)

    do{
        audioPlayer = try AVAudioPlayer(contentsOfURL:sound)
        audioPlayer.prepareToPlay()
        audioPlayer.play()
    }catch {
        print("Error getting the audio file")
    }
} else {
    print("Error: Can't find file. Path is nil") // - This is always printed when I use the variable result from the switch
}