AVAudioPlayer时间显示 [英] AVAudioPlayer time display

问题描述

我有一个简单的mp3通过AVAudioPlayer播放，我希望能够显示剩余的时间。

I have a simple mp3 playing through AVAudioPlayer and I want to be able to display how much time is left.

我知道答案包括从 AVAudioPlayer.currentTime AVAudioPlayer.duration c $ c>但是我不知道如何实现一个在播放时计算它的函数（比如我想在的Actionscript中的onEnterFrame）。目前 currentTime 是静态的，即零。

I know the answer includes subtracting AVAudioPlayer.duration from AVAudioPlayer.currentTime but I don't know how to implement a function which calculates it while it's playing (like an onEnterFrame in Actionscript I guess). At present currentTime is static, i.e. zero.

推荐答案

我会去对于NSTimer。安排它在媒体播放时每秒运行一次，这样你就可以用剩下的时间更新你的UI。

I would go for an NSTimer. Schedule it to run every second while the media is played and so you can keep your UI updated with the time left.

// Place this where you start to play
NSTimer * myTimer = [NSTimer scheduledTimerWithTimeInterval:1.0
                                                     target:self
                                                   selector:@selector(updateTimeLeft)
                                                   userInfo:nil
                                                    repeats:YES];

并创建更新UI的方法：

And create the method to update you UI:

- (void)updateTimeLeft {
    NSTimeInterval timeLeft = self.player.duration - self.player.currentTime;

    // update your UI with timeLeft
    self.timeLeftLabel.text = [NSString stringWithFormat:@"%f seconds left", timeLeft];
}

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