如何在AVPlayer上显示缓冲区进度？

Question

我有一个音乐播放器应用程序，允许用户从服务器流式传输歌曲。我已经能够使用AVPlayer从网址流式传输歌曲了。我想实现以下目标：

我试图将此How to get file size and current file size from NSURL for AVPlayer iOS4.0帖子的最高回答转换为swift，但我找不到“kLoadedTimeRanges”。

这是我的代码：

override func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [NSObject : AnyObject], context: UnsafeMutablePointer<Void>) {

    if object as? NSObject == songPlayer && keyPath == "status" {

        if songPlayer?.status == AVPlayerStatus.Failed {

            println("AVPlayerStatusReadyToFailed")

        }else if songPlayer?.status == AVPlayerStatus.ReadyToPlay {

            println("AVPlayerStatusReadyToPlay")
            self.songPlayer!.play()

        }else if songPlayer?.status == AVPlayerStatus.Unknown {

            println("AVPlayerStatusReadyToUnknown")

        }

    }
}

@IBAction func playAction(sender: UIButton) {

    var songUrl = "http://a575.phobos.apple.com/us/r1000/119/Music/v4/67/9d/b0/679db0ba-a7f4-35ea-3bf1-e817e7bcf11f/mzaf_3227008615944938675.aac.m4a"
    var songPlayerItem = self.songPlayer?.currentItem
    self.songPlayer = AVPlayer(URL: NSURL(string: songUrl))
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "playerItemDidReachEnd:", name: AVPlayerItemDidPlayToEndTimeNotification, object: self.songPlayer?.currentItem)

    self.songPlayer?.addObserver(self, forKeyPath: "status", options: nil, context: nil)
    //NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: "updateProgress:", userInfo: nil, repeats: true)

}

我会感激任何建议，使用目标c或swift无关紧要

Answer 1

只需使用

[avPlayerItem addObserver:self forKeyPath:@"loadedTimeRanges" options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew context:nil];

kLoadedTimeRanges可能只是定义为

static NSString *kLoadedTimeRanges = @"loadedTimeRanges";

Answer 2

目标C： 注意：我创建了一个自定义UISlider（Buffer Slider），其中我添加了一个UIProgressView来显示缓冲区进度。下面代码中显示的setBufferValue方法是一个自定义方法，它将设置UIProgressView值

static void *PlayerViewControllerLoadedTimeRangesObservationContext = &PlayerViewControllerLoadedTimeRangesObservationContext;

[self.playerItem addObserver:self forKeyPath:@"loadedTimeRanges" options:NSKeyValueObservingOptionNew context:PlayerViewControllerLoadedTimeRangesObservationContext];

- (void)observeValueForKeyPath:(NSString*) path
                      ofObject:(id)object
                        change:(NSDictionary*)change
                       context:(void*)context
{
    if (context == PlayerViewControllerLoadedTimeRangesObservationContext) {
        NSArray *timeRanges = (NSArray*)[change objectForKey:NSKeyValueChangeNewKey];

        if (timeRanges && [timeRanges count]) {
            CMTimeRange timerange=[[timeRanges objectAtIndex:0]CMTimeRangeValue];
            float bufferTimeValue=CMTimeGetSeconds(timerange.duration)/CMTimeGetSeconds(_player.currentItem.duration);
            [self.playerSlider setBufferValue:bufferTimeValue>.95?1:bufferTimeValue animated:YES];
        }
    }
}