我试图从下面的代码片段中获取照片库中的视频.但我也得到图像列表.如何获得所有视频的列表？我究竟做错了什么？
NSMutableArray* assetURLDictionaries = [[NSMutableArray alloc] init];
xy =[[NSMutableArray alloc]init];
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
void (^assetEnumerator)( ALAsset *,NSUInteger,BOOL *) = ^(ALAsset *result,NSUInteger index,BOOL *stop) {
if(result != nil) {
if([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypeVideo]) {
[assetURLDictionaries addObject:[result valueForProperty:ALAssetPropertyURLs]];
NSLog(@"result is:%@",result);
NSLog(@"asset URLDictionary is:%@",assetURLDictionaries);
NSURL *url= (NSURL*) [[result defaultRepresentation]url];
[library assetForURL:url
resultBlock:^(ALAsset *asset) {
[xy addObject:[UIImage imageWithCGImage:[[asset defaultRepresentation] fullScreenImage]]];
NSLog(@" xy is:%@",xy);
image =[ [UIImageView alloc ] initWithImage:[xy objectAtIndex:0]];
NSLog(@"image is:%@",image);
}
failureBlock:^(NSError *error){ NSLog(@"test:Fail"); } ];
}
}
};
NSMutableArray *assetGroups = [[NSMutableArray alloc] init];
void (^ assetGroupEnumerator) ( ALAssetsGroup *,BOOL *)= ^(ALAssetsGroup *group,BOOL *stop) {
NSLog(@"hello");
if(group != nil) {
[group enumerateAssetsUsingBlock:assetEnumerator];
[assetGroups addObject:group];
NSLog(@"Number of assets in group :%d",[group numberOfAssets]);
NSLog(@"asset group is:%@",assetGroups);
}
};
assetGroups = [[NSMutableArray alloc] init];
[library enumerateGroupsWithTypes:ALAssetsGroupAll
usingBlock:assetGroupEnumerator
failureBlock:^(NSError *error) {NSLog(@"A problem occurred");}];
解决方法
您需要在枚举期间向组中添加ALAssetsFilter.这是一个基本的例子：
ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];
[library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group,BOOL *stop) {
if (group) {
[group setAssetsFilter:[ALAssetsFilter allVideos]];
[group enumerateAssetsUsingBlock:^(ALAsset *asset,BOOL *stop){
if (asset){
NSDictionary *Meta = [[asset defaultRepresentation] Metadata];
}
}];
}
} failureBlock:^(NSError *error) {
NSLog(@"error enumerating AssetLibrary groups %@\n",error);
}];
为了将来参考,available filters是：
- allPhotos - allVideos - allAssets
