如何获取mp3文件的专辑封面

Question

我正在开发一个音频播放器。 我成功获取了mp3文件的其他信息。 但无法获取 mp3 文件的专辑封面。 使用这段代码我得到了 mp3 文件信息。

- (NSDictionary *)songID3Tags
{   
AudioFileID fileID = nil;
OSStatus error = noErr;
error = AudioFileOpenURL((CFURLRef)self.filePath, kAudioFileReadPermission, 0, &fileID);
    if (error != noErr) {
    NSLog(@"AudioFileOpenURL failed");
}
UInt32 id3DataSize  = 0;
    char *rawID3Tag    = NULL;

error = AudioFileGetPropertyInfo(fileID, kAudioFilePropertyID3Tag, &id3DataSize, NULL);
if (error != noErr)
    NSLog(@"AudioFileGetPropertyInfo failed for ID3 tag");

rawID3Tag = (char *)malloc(id3DataSize);
if (rawID3Tag == NULL)
    NSLog(@"could not allocate %lu bytes of memory for ID3 tag", id3DataSize);

error = AudioFileGetProperty(fileID, kAudioFilePropertyID3Tag, &id3DataSize, rawID3Tag);
if( error != noErr )
    NSLog(@"AudioFileGetPropertyID3Tag failed");

UInt32 id3TagSize = 0;
UInt32 id3TagSizeLength = 0;

error = AudioFormatGetProperty(kAudioFormatProperty_ID3TagSize, id3DataSize, rawID3Tag, &id3TagSizeLength, &id3TagSize);

if (error != noErr) {
    NSLog( @"AudioFormatGetProperty_ID3TagSize failed" );
    switch(error) {
        case kAudioFormatUnspecifiedError:
            NSLog( @"Error: audio format unspecified error" ); 
            break;
        case kAudioFormatUnsupportedPropertyError:
            NSLog( @"Error: audio format unsupported property error" ); 
            break;
        case kAudioFormatBadPropertySizeError:
            NSLog( @"Error: audio format bad property size error" ); 
            break;
        case kAudioFormatBadSpecifierSizeError:
            NSLog( @"Error: audio format bad specifier size error" ); 
            break;
        case kAudioFormatUnsupportedDataFormatError:
            NSLog( @"Error: audio format unsupported data format error" ); 
            break;
        case kAudioFormatUnknownFormatError:
            NSLog( @"Error: audio format unknown format error" ); 
            break;
        default:
            NSLog( @"Error: unknown audio format error" ); 
            break;
    }
}   

CFDictionaryRef piDict = nil;
UInt32 piDataSize = sizeof(piDict);

error = AudioFileGetProperty(fileID, kAudioFilePropertyInfoDictionary, &piDataSize, &piDict);
if (error != noErr)
    NSLog(@"AudioFileGetProperty failed for property info dictionary");

free(rawID3Tag);

return (NSDictionary*)piDict;
}

我知道通过 kAudioFilePropertyAlbumArtwork 我可以获得 mp3 文件的专辑封面，但我不知道如何获得它。

Answer 1

    - (NSArray *)artworksForFileAtPath:(NSString *)path {
NSMutableArray *artworkImages = [NSMutableArray array];
NSURL *u = [NSURL fileURLWithPath:path];
AVURLAsset *a = [AVURLAsset URLAssetWithURL:u options:nil];
 NSArray *artworks = [AVMetadataItem metadataItemsFromArray:a.commonMetadata  withKey:AVMetadataCommonKeyArtwork keySpace:AVMetadataKeySpaceCommon];

for (AVMetadataItem *i in artworks)
{
    NSString *keySpace = i.keySpace;
    UIImage *im = nil;

    if ([keySpace isEqualToString:AVMetadataKeySpaceID3])
    {
        NSDictionary *d = [i.value copyWithZone:nil];
        im = [UIImage imageWithData:[d objectForKey:@"data"]];
    }
    else if ([keySpace isEqualToString:AVMetadataKeySpaceiTunes])
        im = [UIImage imageWithData:[i.value copyWithZone:nil]];

    if (im)
        [artworkImages addObject:im];
}
NSLog(@"array description is %@", [artworkImages description]);
return artworkImages; }

上面的代码返回 mp3 文件的 album_art。 其中 path 是音频文件路径。