iOS AVFoundation:如何从mp3文件中提取图稿？
iOS AVFoundation:如何从mp3文件中提取图稿？
提问于 2012-12-25 20:43:18
我的代码：
- (void)metadata {
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:self.fileURL options:nil];
NSArray *artworks = [AVMetadataItem metadataItemsFromArray:asset.commonMetadata withKey:AVMetadataCommonKeyArtwork keySpace:AVMetadataKeySpaceCommon];
NSArray *titles = [AVMetadataItem metadataItemsFromArray:asset.commonMetadata withKey:AVMetadataCommonKeyTitle keySpace:AVMetadataKeySpaceCommon];
NSArray *artists = [AVMetadataItem metadataItemsFromArray:asset.commonMetadata withKey:AVMetadataCommonKeyArtist keySpace:AVMetadataKeySpaceCommon];
NSArray *albumNames = [AVMetadataItem metadataItemsFromArray:asset.commonMetadata withKey:AVMetadataCommonKeyAlbumName keySpace:AVMetadataKeySpaceCommon];
AVMetadataItem *artwork = [artworks objectAtIndex:0];
AVMetadataItem *title = [titles objectAtIndex:0];
AVMetadataItem *artist = [artists objectAtIndex:0];
AVMetadataItem *albumName = [albumNames objectAtIndex:0];
if ([artwork.keySpace isEqualToString:AVMetadataKeySpaceID3]) {
NSDictionary *dictionary = [artwork.value copyWithZone:nil];
self.currentSongArtwork = [UIImage imageWithData:[dictionary objectForKey:@"data"]];
}
else if ([artwork.keySpace isEqualToString:AVMetadataKeySpaceiTunes]) {
self.currentSongArtwork = [UIImage imageWithData:[artwork.value copyWithZone:nil]];
}
self.currentSongTitle = [title.value copyWithZone:nil];
self.currentSongArtist = [artist.value copyWithZone:nil];
self.currentSongAlbumName = [albumName.value copyWithZone:nil];
self.currentSongDuration = self.audioPlayer.duration;
}这适用于从m4a文件中提取图稿，但不适用于mp3文件。如果asset指向mp3文件，则artworks为空。我做错了什么?我该如何改正？
回答 3
Stack Overflow用户
回答已采纳
发布于 2012-12-27 19:50:39
我发现当图像被同步设置时，图片被异步加载。我是这样解决的：
- (void)metadata {
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:self.fileURL options:nil];
NSArray *titles = [AVMetadataItem metadataItemsFromArray:asset.commonMetadata withKey:AVMetadataCommonKeyTitle keySpace:AVMetadataKeySpaceCommon];
NSArray *artists = [AVMetadataItem metadataItemsFromArray:asset.commonMetadata withKey:AVMetadataCommonKeyArtist keySpace:AVMetadataKeySpaceCommon];
NSArray *albumNames = [AVMetadataItem metadataItemsFromArray:asset.commonMetadata withKey:AVMetadataCommonKeyAlbumName keySpace:AVMetadataKeySpaceCommon];
AVMetadataItem *title = [titles objectAtIndex:0];
AVMetadataItem *artist = [artists objectAtIndex:0];
AVMetadataItem *albumName = [albumNames objectAtIndex:0];
NSArray *keys = [NSArray arrayWithObjects:@"commonMetadata", nil];
[asset loadValuesAsynchronouslyForKeys:keys completionHandler:^{
NSArray *artworks = [AVMetadataItem metadataItemsFromArray:asset.commonMetadata
withKey:AVMetadataCommonKeyArtwork
keySpace:AVMetadataKeySpaceCommon];
for (AVMetadataItem *item in artworks) {
if ([item.keySpace isEqualToString:AVMetadataKeySpaceID3]) {
NSDictionary *d = [item.value copyWithZone:nil];
self.currentSongArtwork = [UIImage imageWithData:[d objectForKey:@"data"]];
} else if ([item.keySpace isEqualToString:AVMetadataKeySpaceiTunes]) {
self.currentSongArtwork = [UIImage imageWithData:[item.value copyWithZone:nil]];
}
}
}];
self.currentSongTitle = [title.value copyWithZone:nil];
self.currentSongArtist = [artist.value copyWithZone:nil];
self.currentSongAlbumName = [albumName.value copyWithZone:nil];
self.currentSongDuration = self.audioPlayer.duration;
}Stack Overflow用户
发布于 2012-12-27 05:29:35
我刚刚在这里找到了这个问题的答案：How can I extract metadata from mp3 file in ios development，现在我想知道为什么这段代码不能在m4a文件上工作。我从您的代码中摘录了一点，并给出了以下似乎适用于m4a和mp3的代码。请注意，我将适用于mp3的代码作为一个开放的else子句，不带限定符-如果任何人在这方面获得了更多经验，欢迎他们进行改进！
- (void)getMetaDataForSong:(MusicItem *)musicItem {
AVAsset *assest;
// filePath looks something like this: /var/mobile/Applications/741647B1-1341-4203-8CFA-9D0C555D670A/Library/Caches/All Summer Long.m4a
NSURL *fileURL = [NSURL fileURLWithPath:musicItem.filePath];
NSLog(@"%@", fileURL);
assest = [AVURLAsset URLAssetWithURL:fileURL options:nil];
NSLog(@"%@", assest);
for (NSString *format in [assest availableMetadataFormats]) {
for (AVMetadataItem *item in [assest metadataForFormat:format]) {
if ([[item commonKey] isEqualToString:@"title"]) {
musicItem.strSongTitle = (NSString *)[item value];
}
if ([[item commonKey] isEqualToString:@"artist"]) {
musicItem.strArtistName = (NSString *)[item value];
}
if ([[item commonKey] isEqualToString:@"albumName"]) {
musicItem.strAlbumName = (NSString *)[item value];
}
if ([[item commonKey] isEqualToString:@"artwork"]) {
UIImage *img = nil;
if ([item.keySpace isEqualToString:AVMetadataKeySpaceiTunes]) {
img = [UIImage imageWithData:[item.value copyWithZone:nil]];
}
else { // if ([item.keySpace isEqualToString:AVMetadataKeySpaceID3]) {
NSData *data = [(NSDictionary *)[item value] objectForKey:@"data"];
img = [UIImage imageWithData:data] ;
}
musicItem.imgArtwork = img;
}
}
}
}Stack Overflow用户
发布于 2020-01-18 21:30:41
正如Ryan Heitner在给Andy Weinstein的评论中指出的那样，从AVMetadataKeySpaceID3检索二进制艺术作品数据的方式已经从IOS7更改为IOS8。在如今的ID3案例中，盲目地将item转换为NSDictionary将会崩溃。要使代码防弹，只需检查dataValue，否则检查类。事实上，今天的item.value指向item.dataValue并拥有NSData类。
- (UIImage*)imageFromItem:(AVMetadataItem*)item
{
NSData* data=nil;
if (item.dataValue!=nil) {
data=item.dataValue;
} else if ([item.value isKindOfClass:NSData.class]) { //never arrive here nowadays
data=(NSData*)item.value;
} else if ([item.value isKindOfClass:NSDictionary.class]) { //never arrive here nowadays...
NSDictionary* dict=(NSDictionary*)item.value;
data=dict[@"data"];
}
if (data==nil) {
return nil;
}
return [UIImage imageWithData:data];
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/14030746
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