swift - fatal error : unexpectedly found nil while unwrapping an Optional value (Swift)

Question

我总是遇到 fatal error :在展开可选值时意外发现 nil。但如果我查看 fileURL 变量，它有一些值。请让我知道我在这里错过了什么:

错误:

Optional(http:/files.parsetfss.com/461a4eda-d153-4d46-bd85-28ddd355a94c/tfss-03d4eb57-51cb-424d-8c90-2d8a89429203-00255--How_To_Build_A_Loving_Family.mp3 -- file:///)   
fatal error: unexpectedly found nil while unwrapping an Optional value

代码:

        if let audioFile = object["audioFile"] as? PFFile {

            var audioPath: String = audioFile.url!

            var fileURL = NSURL(fileURLWithPath: audioPath as String)
            println(fileURL)
            audioPlayer = AVAudioPlayer(contentsOfURL: fileURL, error: nil)

            audioPlayer.volume = volumeSlider.value

            audioPlayer.play()

        }

Answer 1

这段代码可以很好地处理您的 URL:

let url = "http://files.parsetfss.com/461a4eda-d153-4d46-bd85-28ddd355a94c/tfss-03d4eb57-51cb-424d-8c90-2d8a89429203-00255--How_To_Build_A_Loving_Family.mp3"

    let soundData = NSData(contentsOfURL: NSURL(string: url)!)

    var error: NSError?
    self.audioPlayer = AVAudioPlayer(data: soundData, error: &error)
    if audioPlayer == nil
    {
        if let e = error
        {
            println(e.localizedDescription)
        }
    }

    audioPlayer!.volume   = 1.0
    audioPlayer!.prepareToPlay()

    audioPlayer!.play()

通过这种方式，您可以将音频转换为数据，这将需要一些时间来播放您的音频。

这是另一种现场播放歌曲的方式:

let url = audioFile.url!
let playerItem = AVPlayerItem( URL:NSURL( string:url ) )
player = AVPlayer(playerItem:playerItem)
player.rate = 1.0;
player.play()