我正在尝试通过以下代码从照片库中获取视频。但我也获取图像列表。如何获取所有视频的列表？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");}];
您需要在枚举期间将 ALAssetsFilter 添加到组中。这是一个基本示例：
ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];
[library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
if (group) {
[group setAssetsFilter:[ALAssetsFilter allVideos]];
[group enumerateAssetsUsingBlock:^(ALAsset *asset, NSUInteger index, 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，可用的过滤器 https://developer.apple.com/library/ios/documentation/AssetsLibrary/Reference/ALAssetsFilter_Class/Reference/Reference.html are:
- allPhotos
- allVideos
- allAssets
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