如何使Progressbar(UISlider)在我的应用程序中动态工作？

Question

可能重复:
用于控制AVAudioPlayer的UISlider

我正在尝试为iPhone开发一个简单的音频播放器应用程序,我需要实现必须根据歌曲(mediafile)长度运行的进度条.我怎么能完成这个？我可以使用带定时器的滑块吗？任何帮助都提前感谢,谢谢.

Answer 1

如果您正在播放音频,AVPlayer则可以使用其**addPeriodicTimeObserverForInterval**:方法更新UISlider.例如,如果滑块的名称是playerScrubber:

    AVPlayerItem *newPlayerItem = [[AVPlayerItem alloc] initWithAsset:<your asset>];
    AVPlayer* player = [[AVPlayer alloc] initWithPlayerItem:newPlayerItem];

    CMTime interval = CMTimeMake(33, 1000);  // 30fps
    id playbackObserver = [player addPeriodicTimeObserverForInterval:interval queue:dispatch_get_current_queue() usingBlock: ^(CMTime time) {
            CMTime endTime = CMTimeConvertScale (player.currentItem.asset.duration, player.currentTime.timescale, kCMTimeRoundingMethod_RoundHalfAwayFromZero);
            if (CMTimeCompare(endTime, kCMTimeZero) != 0) {
                    double normalizedTime = (double) player.currentTime.value / (double) endTime.value;
                    playerScrubber.value = normalizedTime;
            }
        }];

以后当你完成时:

[player removeTimeObserver:playbackObserver];

祝好运!