Swift 无法停止 AVPlayer

如果将player声明为可选变量，则可以将播放器设置为nil以取消分配.

这是一个愚蠢的例子，但它说明了发生了什么:

import UIKit
import AVFoundation

class ViewController: UIViewController {

    @IBOutlet weak var btnPlay: UIButton!

    var player:AVPlayer?

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    @IBAction func btnPress(sender: AnyObject) {
        if (btnPlay.titleLabel?.text == "Play") {
            initPlayer()
            btnPlay.setTitle("Stop", forState: UIControlState.Normal)
        } else {
            stopPlayer()
            btnPlay.setTitle("Play", forState: UIControlState.Normal)
        }
    }

    func initPlayer()  {
        if let play = player {
            print("playing")
            play.play()
        } else {
            print("player allocated")
            player = AVPlayer(URL: NSURL(string: "http://streaming.radio.rtl.fr/rtl-1-48-192")!)
            print("playing")
            player!.play()
        }
    }

    func stopPlayer() {
        if let play = player {
            print("stopped")
            play.pause()
            player = nil
            print("player deallocated")
        } else {
            print("player was already deallocated")
        }
    }
}