ALAssetsLibrary delete ALAssetsGroup / ALAsset - ios5

Question

I have created "photos album" from my App, using IOS AssetsLibrary.
Reading ALAssetsLibrary,ALAssetsGroup and ALAsset documentations, i have seen methods to "addAsset","addAssetsGroupAlbumWithName".
Is there a way to delete PROGRAMMATICALLY my ALAssetsGroup and ALAsset.
(the property 'editable' suppose to be TRUE because i create this data).

Answer 1

You can only delete the ALAsset which is created by your app with document API [ALAsset setImageData:metadata:completionBlock:] (But I have not found any API to delete a ALAssetGroup).
1). Add an image "photo.jpg" to your project
2). Save an image to asset library:
ALAssetsLibrary *lib = [ALAssetsLibrary new];
UIImage *image = [UIImage imageNamed:#"photo.jpg"];
[lib writeImageToSavedPhotosAlbum:image.CGImage metadata:#{} completionBlock:^(NSURL *assetURL, NSError *error) {
NSLog(#"Write image %# to asset library. (Error %#)", assetURL, error);
}];
3). Go to default gallery, you will find photo.jpg in your "Saved Photos" album.
4). Delete this image from asset library:
ALAssetsLibrary *lib = [ALAssetsLibrary new];
[lib enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
[group enumerateAssetsUsingBlock:^(ALAsset *asset, NSUInteger index, BOOL *stop) {
if(asset.isEditable) {
[asset setImageData:nil metadata:nil completionBlock:^(NSURL *assetURL, NSError *error) {
NSLog(#"Asset url %# should be deleted. (Error %#)", assetURL, error);
}];
}
}];
} failureBlock:^(NSError *error) {
}];
5). Go to default gallery, you will find photo.jpg has already been deleted.

Answer 2

This is not possible using any documented API. Only the photos app can delete Albums. If you want this feature to be added to iOS, I would fill a feature request at https://feedbackassistant.apple.com/.

Answer 3

in ios8 deleting photos might be possible using the Photos Framework
Please check the documentation of Photos Framework
For deleting assets refer to PHAssetChangeRequest
+ (void)deleteAssets:(id<NSFastEnumeration>)assets
where assets is an array of PHAsset objects to be deleted.
For deleting collections refer to PHAssetCollectionChangeRequest
+ (void)deleteAssetCollections:(id<NSFastEnumeration>)assetCollections
https://developer.apple.com/library/prerelease/ios/documentation/Photos/Reference/PHAssetChangeRequest_Class/index.html#//apple_ref/occ/clm/PHAssetChangeRequest/deleteAssets:

Answer 4

As Ted said, this is now possible in iOS 8 using the Photos service. It's pretty clean actually. You need to submit a change request to the photolibrary. Here's an example.
[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
[PHAssetChangeRequest deleteAssets:arrayOfPHAssets];
} completionHandler:^(BOOL success, NSError *error) {
NSLog(#"Finished deleting asset. %#", (success ? #"Success." : error));
}];
Make sure you've imported Photos, and gotten authorization from the user. (Which you probably did to show the image already)
PHAssetchangeRequest - deleteAssets
https://developer.apple.com/library/prerelease/ios/documentation/Photos/Reference/PHAssetChangeRequest_Class/index.html#//apple_ref/occ/clm/PHAssetChangeRequest/deleteAssets:
PHPhotoLibrary Class - authorizationStatus
https://developer.apple.com/library/ios/documentation/Photos/Reference/PHPhotoLibrary_Class/#//apple_ref/occ/clm/PHPhotoLibrary/authorizationStatus

Answer 5

evanchin is correct. Further more, if you want to do this in Xamarin.iOS (aka monotouch):
var lib = new ALAssetsLibrary();
lib.Enumerate(ALAssetsGroupType.All, (ALAssetsGroup group, ref bool libStop) =>
{
if (group == null)
{
return;
}
group.Enumerate((ALAsset asset, int index, ref bool groupStop) =>
{
if (asset != null && asset.Editable)
{
asset.SetImageDataAsync(new NSData(IntPtr.Zero), new NSDictionary(IntPtr.Zero));
}
});
}, error => { });
This code will delete all images that your app added to the ALAssetsLibrary.

Answer 6

You may delete any asset in the library using documented API ONLY.
over writing the [ALAsset isEditable] function:
#implementation ALAsset(DELETE)
-(BOOL)isEditable{
return YES;
}
#end
like evanchin said, delete the asset:
ALAssetsLibrary *lib = [ALAssetsLibrary new];
[lib enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos
usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
[group enumerateAssetsUsingBlock:^(ALAsset *asset, NSUInteger index, BOOL *stop) {
if(asset.isEditable) {
[asset setImageData:nil
metadata:nil
completionBlock:^(NSURL *assetURL, NSError *error) {
NSLog(#"Asset url %# should be deleted. (Error %#)", assetURL, error);
}];
}
}];
} failureBlock:^(NSError *error) {
}];