Get the artwork of an mp3 audio file.

artworkblock.mm

- (void)artworksForFileAtPath:(NSString *)path block:(void(^)(NSArray *artworkImages))block {
    
    NSURL *url = [NSURL fileURLWithPath:path];
    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:url options:nil];
    NSArray *keys = [NSArray arrayWithObjects:@"commonMetadata", nil];
    [asset loadValuesAsynchronouslyForKeys:keys completionHandler:^{
        NSArray *artworks = [AVMetadataItem metadataItemsFromArray:asset.commonMetadata withKey:AVMetadataCommonKeyArtwork keySpace:AVMetadataKeySpaceCommon];
        
        NSMutableArray *artworkImages = [NSMutableArray array];
        for (AVMetadataItem *item in artworks) {
            NSString *keySpace = item.keySpace;
            
            UIImage *image = nil;
            
            if ([keySpace isEqualToString:AVMetadataKeySpaceID3]) {
                NSDictionary *d = [item.value copyWithZone:nil];
                image = [UIImage imageWithData:[d objectForKey:@"data"]];
                [d release];
            } else if ([keySpace isEqualToString:AVMetadataKeySpaceiTunes]) {
                NSData *data = [item.value copyWithZone:nil];
                image = [UIImage imageWithData:data];
                [data release];
            }
            
            if (image != nil) {
                [artworkImages addObject:image];
            }
        }
        
        if (block) {
            block(artworkImages);
        }
    }];
}