从流中获取元数据有问题吗？

Question

I am trying to obtain the metadata such as Artist name / Track name for my URL, however I don't see, to be getting it at all, I am not quite sure what I am missing, the audio loads up and plays just fine:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    self.mainTitle.text = _stationName;

    NSString *u = @"http://pub1.sky.fm:80/sky_solopiano";

    NSURL *url = [NSURL URLWithString:u];

    radiosound = [[AVPlayer alloc] initWithURL:url];

    [radiosound play];

}

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    AVPlayerItem * item = (AVPlayerItem*)object;
    NSLog(@"%@", item.timedMetadata);


}

Update Per the suggestion of a member in this question, I tried implementing

AVAsset *info = radiosound.currentItem.asset;

    NSLog(@"%@",info);

Instead of

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
        AVPlayerItem * item = (AVPlayerItem*)object;
        NSLog(@"%@", item.timedMetadata);


    }

But this only returns data that I already know and does not refresh, it currently returns:

<AVURLAsset: 0x109c7ccf0, URL = http://pub1.sky.fm:80/sky_solopiano>

Answer 1

You've overridden/implemented the observer hook on NSObject, however you didn't set up property observing for the AVPlayer anywhere, so this method will never fire.

I think what you're actually interested in is:

radiosound.currentItem.asset

. . . which you can use immediately after you've alloc/init'd your radiosound instance.

The available properties on this class are here

To obtain docs for a given class:

• Google the class name - it will almost always return results.
• Option-click the class in Xcode
• Use a documentation browser like Dash

Key-value observing (KVO)

You probably don't need KVO in this case, however its something you should definitely check up on. For more information there are the Apple docs, as well as loads of tutorials. Perhaps this one ?