ios - 检测 AVQueuePlayer 中的当前项目并知道它何时更改？

Question

我目前有一个 AVQueuePlayer 依次播放几个 .aif 文件。当它通过每个音频时，我想执行与该特定声音相关的操作（例如更改图像视图的 uiimage）。

我的问题是正确设置 NSNotification。我已将其设置为在队列完成最后一个对象时通知我，但我无法接收到每个当前项目的通知。这是我所拥有的：

//Setting Up My Queue List
    yellowVoice = [[AVPlayerItem alloc] initWithURL:[NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/YellowVoice.aif", [[NSBundle mainBundle] resourcePath]]]];
    orangeVoice = [[AVPlayerItem alloc] initWithURL:[NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/OrangeVoice.aif", [[NSBundle mainBundle] resourcePath]]]];
    redVoice = [[AVPlayerItem alloc] initWithURL:[NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/RedVoice.aif", [[NSBundle mainBundle] resourcePath]]]];
    pinkVoice = [[AVPlayerItem alloc] initWithURL:[NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/PinkVoice.aif", [[NSBundle mainBundle] resourcePath]]]];

    NSArray *soundEmotions = [NSArray arrayWithObjects:yellowVoice, orangeVoice, redVoice, pinkVoice, nil];

    soundQueue = [AVQueuePlayer queuePlayerWithItems:soundEmotions];

// Notify me when queue reaches the end of the last player item
[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(playerItemDidReachEnd:)
                                                 name:AVPlayerItemDidPlayToEndTimeNotification
                                               object:[soundEmotions lastObject]];

// Notify me when a new player item begins and which one it is
[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(currentItemIs:)
                                                 name:AVPlayerItemDidPlayToEndTimeNotification
                                               object:[soundQueue currentItem]];

[soundQueue play];

我觉得我被 name 参数困住了。我应该把它改成什么？当它切换时，我如何找出当前正在播放的播放器项目的名称？谢谢！

//Here is one of the things I want to do with that info
- (void)currentItemIs:(NSNotification *)notification {

    if (soundQueue.currentItem ==yellowVoice) {

        UIImage * yellowImage = [UIImage imageNamed:@"yellow.png"];
        [UIView transitionWithView:self.view
                          duration:1.0f
                           options:UIViewAnimationOptionTransitionCrossDissolve
                        animations:^{
                            mainImage.image = yellowImage;
                        } completion:NULL];


    }


    if (soundQueue.currentItem ==yellowVoice) {

        UIImage * orangeImage = [UIImage imageNamed:@"orange.png"];
        [UIView transitionWithView:self.view
                          duration:1.0f
                           options:UIViewAnimationOptionTransitionCrossDissolve
                        animations:^{
                            mainImage.image = orangeImage;
                        } completion:NULL];


    }


}

Answer 1

- (void)currentItemIs:(NSNotification *)notification 
{
   AVPlayerItem *p = [notification object];
   if (p ==yellowVoice) {
   //rest of the code
   }
}

Answer 2

Bhushan 的答案是缺少触发每个项目通知的循环，因此：

for (AVPlayerItem *playerItem in queuePlayer.items) {
            [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(currentItemIs:)  name:AVPlayerItemDidPlayToEndTimeNotification object:playerItem];
        }