十五、AVAudioPlayer播放音乐注意点

1.必须要用 AVAudioSession，否则木有声音啊。
2.不要把 AVAudioPlayer 当做局部变量，要定义成全局变量
3.要找好路径，这里用 mainBundle，不要搞错。

    private func playMusic() {
        
        let musicPath = Bundle.main.path(forResource: "money", ofType: "mp3")
        let fileUrl = NSURL.fileURL(withPath: musicPath ?? " ")
        do {
            let session = AVAudioSession.sharedInstance()
            try session.setCategory(AVAudioSessionCategoryPlayback)
            try session.setActive(true)
            audioPlay = try AVAudioPlayer.init(contentsOf: fileUrl)
            audioPlay.numberOfLoops = 0
            audioPlay.volume = 0.5
            audioPlay.currentTime = 0
            audioPlay.prepareToPlay()
            audioPlay.play()
        }
        catch {
            debugLog(error)
        }
    }