Question

IOS开发视频播放UIslider问题

mpmovieplayercontroller. currentPlaybackTime;设置视频seek指定秒播放，比如170秒，
拖条用的时 uislider，滑块经常被 拖 回去一点，很不爽！，到底什么问题？是不是bug？

打印研究发现给currentPlaybackTime设置时间，会回退几秒
为什么经常会 回退 几秒开始播放？设置170秒，回退164，167，163，或169，回退几秒开始播放，bug？
一开始以为网络问题，可是视频完成加载完了，也会有这个问题！

10次一般有5次这样的情况！ 有人遇到吗？

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Answer 1

这有一个例子：
iPhone – Add an UISlider For AVAudioPlayer
We can use AVAudioPlayer to play music. Now i want to add an UISlider as the music progress bar and user can fast skip the music.

Now i have a play button in the view and when user click it, i will play the music file as well as the following method.

* playButtonClicked – Run when the play button is clicked
* updateSlider – Run in 1 second interval to update the UISlider
* sliderChange – Fast skip the music when user scroll the UISlider

Here comes the code - (IBAction)playButtonClicked:(id)sender {

// Read the file from resource folder and set it in the avAudioPlayer

NSURL *fileUrl = [[NSURL alloc] initFileURLWithPath:[[NSBundle mainBundle] pathForResource:@"musicFile" ofType:@"caf"]];

avAudioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:fileUrl error:nil];

[avAudioPlayer setDelegate:self];

[avAudioPlayer setVolume:1.0];

// Set a timer which keep getting the current music time and update the UISlider in 1 sec interval

sliderTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateSlider) userInfo:nil repeats:YES];

// Set the maximum value of the UISlider

aSlider.maximumValue = avAudioplayer.duration;

// Set the valueChanged target

[aSlider addTarget:self action:@selector(sliderChanged:) forControlEvents:UIControlEventValueChanged];

// Play the audio

[avAudioPlayer prepareToPlay];

[avAudioPlayer play];

}

- (void)updateSlider {

// Update the slider about the music time

aSlider.value = avAudioPlayer.currentTime;

}

- (IBAction)sliderChanged:(UISlider *)sender {

// Fast skip the music when user scroll the UISlider

[avAudioPlayer stop];

[avAudioPlayer setCurrentTime:aSlider.value];

[avAudioPlayer prepareToPlay];

[avAudioPlayer play];

}

// Stop the timer when the music is finished (Need to implement the AVAudioPlayerDelegate in the Controller header)

- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag {

// Music completed

if (flag) {

[sliderTimer invalidate];

}

}
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