ios - 如何连续检查 AVAudioplayer 是否已在 Swift 中播放完毕？

Question

我制作了一个简单的播放音频的应用程序。现在我想在音频播放完毕后自动将“暂停”按钮更改为“播放”。我该如何检查？这是代码:

import UIKit
import AVFoundation

class ViewController: UIViewController {
@IBOutlet weak var PausePlay: UIButton!
var BackgroundAudio = AVAudioPlayer(contentsOfURL: NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("M.I.A.-DoubleBubbleTrouble", ofType: "mp3")!), error: nil)

override func viewDidLoad() {
    super.viewDidLoad()        
    BackgroundAudio.play()

}

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

@IBAction func Stop(sender: AnyObject) {
    if(BackgroundAudio.playing) {
    BackgroundAudio.stop()
    BackgroundAudio.currentTime = 0
    PausePlay.setTitle("Play", forState: .Normal)
    } else {
        BackgroundAudio.currentTime = 0
    }
}

@IBAction func Restart(sender: AnyObject) {
    if(BackgroundAudio.playing==false){
        PausePlay.setTitle("Pause", forState: .Normal)
    }
    BackgroundAudio.stop()
    BackgroundAudio.currentTime = 0
    BackgroundAudio.play()
}

@IBAction func PausePlay(sender: AnyObject) {
    if(BackgroundAudio.playing){
        BackgroundAudio.stop()
        PausePlay.setTitle("Play", forState: UIControlState.Normal)
    } else {
        BackgroundAudio.play()
        PausePlay.setTitle("Pause", forState: .Normal)
    }
}

if (BackgroundAudio.playing == false) {
PausePlay.setTitle("Play", forState: .Normal)
}   
}

最后一个 if 语句应该在函数内部，但是我该如何(连续)调用该函数？

Answer 1

您不必不断检查 - 您应该改为在 View Controller 中实现 AVAudioPlayerDelegate 协议(protocol):https://developer.apple.com/library/ios/documentation/AVFoundation/Reference/AVAudioPlayerDelegateProtocolReference/index.html#//apple_ref/occ/intfm/AVAudioPlayerDelegate/audioPlayerDidFinishPlaying:successfully :

参见:audioPlayerDidFinishPlaying:成功:。我想你会发现它做的和你想做的完全相反，这实际上是正确的方法。这样，您的播放器将简单地调用您定义的“结束”函数。