iOS 8专辑封面

从iOS 8开始,来自iPad和iPhone设备的专辑封面的所有数据阵列都返回一个空数组.从本地文件(NSBundle)中提取时,我可以获得专辑封面或封面艺术,但从iTunes或设备本身购买的任何歌曲都会返回空白.

我已经更新到最新的XCode,两台设备上的最新iOS以及iTunes.我已经在iPad 4,iPad Air,iPhone 5,iPhone 6上进行了测试.希望有人知道发生了什么,它现在似乎是iOS 8中的一个已知错误.此外,我可以播放资产并检索歌曲名称和艺术家等内容.

MPMediaQuery *songQuery = [MPMediaQuery songsQuery];
NSArray *itemsFromGenericQuery = [songQuery items];
NSMutableArray *songsList = [[NSMutableArray alloc] initWithArray:itemsFromGenericQuery];
MPMediaItem *mediaItem = (MPMediaItem *)[songsList objectAtIndex:0];

NSURL *url = [mediaItem valueForProperty:MPMediaItemPropertyAssetURL];
AVAsset *asset = [[AVURLAsset alloc] initWithURL:url options:nil];
NSArray *commonArray = [assets commonMetadata];

//Test A
NSArray *albumArray = [AVMetadataItem metadataItemsFromArray:commonArray filteredByIdentifier:AVMetadataIdentifieriTunesMetadataCoverArt];
NSLog(@"commonArray = %lu",(unsigned long)[commonArray count]); //Returns 3
NSLog(@"albumArray has %lu",(unsigned long)[albumArray count]); //Returns 0 or null

//Test B
for (AVMetadataItem *metadataItem in asset.commonMetadata) {

    if ([metadataItem.commonKey isEqualToString:@"artwork"]){
        NSDictionary *imageDataDictionary = (NSDictionary *)metadataItem.value;
        NSData *imageData = [imageDataDictionary objectForKey:@"data"];
        UIImage *image = [UIImage imageWithData:imageData];
        coverArtImage.image = image;
    }
}

//Test C
for (AVMetadataItem *item in commonArray) {

    if ([item.keySpace isEqualToString:AVMetadataKeySpaceiTunes]) {
        NSData *newImage = [item.value copyWithZone:nil];
        coverArtImage.image = [UIImage imageWithData:newImage];
    }

}

//Test D
for (AVMetadataItem *item in asset.metadata) {

    if ([item.commonKey isEqualToString:@"artwork"]){
        NSDictionary *imageDataDictionary = (NSDictionary *)item.value;
        NSData *imageData = [imageDataDictionary objectForKey:@"data"];
        UIImage *image = [UIImage imageWithData:imageData];
        coverArtImage.image = image;
    }

    if ([item.keySpace isEqualToString:AVMetadataKeySpaceiTunes]) {
        NSData *newImage = [item.value copyWithZone:nil];
        coverArtImage.image = [UIImage imageWithData:newImage];
    }

}