AVAudioPlayer 如何在页面呈现之后按需初始化

在页面中按需初始化 AVAudioPlayer

很多时候我们需要根据页面上内容的情况创建 AVAudioPlayer 对象，已达到降低无谓资源占用等目的。下面我们来看一段代码看起来正确的代码：

override func viewDidAppear(animated: Bool) {

    super.viewDidAppear(animated)

    

    var error: NSError?

    let player = AVAudioPlayer(data: NSData(contentsOfURL: NSURL(string: "https://dl.django.t.taobao.com/rest/1.0/file?acl=5222dc2f6b41f20dae409a7743dc04fb&cID=40001&fileIds=ytQkYL66QaOs_6tYGSRHQQAAAA8AAQIC&name=13-1.mp3&timestamp=1426953600&token=5HwHU8ZKQD-kUh3Yw11nZwAAAAAABSZcAAABw60AAAAPAAEB&uID=")!)!, fileTypeHint: "AVFileTypeMPEGLayer3", error: &error)

    if let e = error {

        println(e.debugDescription)

    } else {

        player.prepareToPlay()

        player.play()

    }

}

上面这段代码看起来毫无问题，实际运行以后也是毫无问题，不报错，就是放不出声，非常奇怪。

一步解决奇怪问题

class ViewController: UIViewController {

    

    var player: AVAudioPlayer!

    

    override func viewDidLoad() {

        super.viewDidLoad()

    }

    override func viewDidAppear(animated: Bool) {

        super.viewDidAppear(animated)

        

        var error: NSError?

        player = AVAudioPlayer(data: NSData(contentsOfURL: NSURL(string: "https://dl.django.t.taobao.com/rest/1.0/file?acl=5222dc2f6b41f20dae409a7743dc04fb&cID=40001&fileIds=ytQkYL66QaOs_6tYGSRHQQAAAA8AAQIC&name=13-1.mp3&timestamp=1426953600&token=5HwHU8ZKQD-kUh3Yw11nZwAAAAAABSZcAAABw60AAAAPAAEB&uID=")!)!, fileTypeHint: "AVFileTypeMPEGLayer3", error: &error)

        if let e = error {

            println(e.debugDescription)

        } else {

            player.prepareToPlay()

            player.play()

        }

    }

}

在此控制器类的顶部事先声明播放器对象，即可成功播放！这个方法对于播放器对象数组、字典依然有效：

var playerArray = Array<AVAudioPlayer>()

var playerDictionary = Dictionary<Int, AVAudioPlayer>()

不让对象的内存被自动回收掉即可。