使用UISlider的AVAudioplayer控件在第一次播放时不显示进度

Question

我正在使用Xcode开发自定义音频播放器。但问题是，当我第一次加载音频数据时滑块进度停止工作虽然audioplayer.current正确设置为slider.value ...

NSError *error2;
self.Audioplayer = [[AVAudioPlayer alloc] initWithData:songFile error:&error2];
if (!error2)
{
    Audioplayer.delegate = self;
    [Audioplayer play];
    self.progressSliderview.value = 0.0f;
    self.progressSliderview.maximumValue = Audioplayer.duration;
    currentTimeUpdateTimer = [NSTimer scheduledTimerWithTimeInterval:0.1
                                                              target:self selector:@selector(updateAudioDisplayplay1)
                                                            userInfo:NULL repeats:YES];
}