如何从ios开发中的mp3文件中提取元数据

我正在使用云存储的ios音乐播放器。

我需要提取标题，艺术家，艺术品等音乐信息。

我有一个叫playit的动作，播放和暂停mp3文件。 它也应该填充一些与mp3文件相关的元数据的UILables和UIImage。 问题是我无法从超过不同的25个mp3文件中提取元数据。 这是我的代码：

文件的URL是正确的，因为audio播放器能够find并播放它，但我不知道为什么avmetadataitem无法获得元数据。

- (IBAction)playIt:(id)sender { AVAudioPlayer *audioPlayer; AVAsset *assest; NSString * applicationPath = [[NSBundle mainBundle] resourcePath]; NSString *secondParentPath = [applicationPath stringByDeletingLastPathComponent]; NSString *soundFilePath = [[secondParentPath stringByAppendingPathComponent:@"fisal1407"] stringByAppendingPathComponent:[musicFiles objectForKey:@"show_id"] ]; NSURL *fileURL = [NSURL URLWithString:[soundFilePath stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding]]; assest = [AVURLAsset URLAssetWithURL:fileURL options:nil]; NSArray *metadata = [assest commonMetadata]; for (NSString *format in metadata) { for (AVMetadataItem *item in [assest metadataForFormat:format]) { if ([[item commonKey] isEqualToString:@"title"]) { filename.text = (NSString *)[item value]; NSLog(@" title : %@", (NSString *)[item value]); } if ([[item commonKey] isEqualToString:@"artist"]) { show_id.text = (NSString *)[item value]; } if ([[item commonKey] isEqualToString:@"albumName"]) { // _albumName = (NSString *)[item value]; } if ([[item commonKey] isEqualToString:@"artwork"]) { NSData *data = [(NSDictionary *)[item value] objectForKey:@"data"]; UIImage *img = [UIImage imageWithData:data] ; imageView.image = img; continue; } } } if (audioPlayer == nil) { audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:fileURL error:&error]; audioPlayer.numberOfLoops = -1; [audioPlayer play]; [sender setImage:[UIImage imageNamed:@"player_044.gif"] forState:UIControlStateNormal]; } else { if (audioPlayer.isPlaying) { [sender setImage:[UIImage imageNamed:@"player_04.gif"] forState:UIControlStateNormal]; [audioPlayer pause]; } else { [sender setImage:[UIImage imageNamed:@"player_044.gif"] forState:UIControlStateNormal]; [audioPlayer play]; } } } 

Answer 1

尝试

 for (NSString *format in [asset availableMetadataFormats]) 

代替

 NSArray *metadata = [assest commonMetadata]; for (NSString *format in metadata) {