Cannot read external Fotos Library with MediaLibrary framework - xcode

Question

I'm trying to read a Fotos Library with the MediaLibrary framework from an external disc ("/Seagate").
Whatever I try out, I only get the data from the default library which is located under "Pictures"
Reading the external library with Fotos app runs perfectly. ( I changed the path in Fotos)
In my app, I tried several options:
connecting to the MediaLibrary using the options dictionary to
include my external device by MLMediaLoadFoldersKey ( see code below). no success
reading mediaGroups with different identifiers. no success
I wonder why I cannot get 2 mediaSources, though I have defined the default folders and my external one
The aspect of lazy loading data from the library should be managed well, as I have set observers for all the steps: library -> sources -> groups -> objects
To point 1:
NSDictionary *options = #{
MLMediaLoadSourceTypesKey: #(MLMediaSourceTypeImage),
MLMediaLoadIncludeSourcesKey: #[MLMediaSourcePhotosIdentifier,MLMediaSourceiPhotoIdentifier],
MLMediaLoadFoldersKey:#[MLMediaLoadFoldersKey,#"//Seagate/Fotos Library"]
if ( mediaLibrary == Nil) {
MLMediaLibrary *MmediaLibrary = [[MLMediaLibrary alloc] initWithOptions:options];
mediaLibrary = MmediaLibrary;
}
[mediaLibrary addObserver:self
forKeyPath:#"mediaSources"
options:0
context:(__bridge void *)#"mediaLibraryLoaded"];
[mediaLibrary mediaSources];
To point 2:
//...
else if (context == (__bridge void *)#"rootMediaGroupLoaded")
{
MLMediaGroup *sharedAlbums = [mediaSource mediaGroupForIdentifier:#"TopLevelAlbums"];
MLMediaGroup *topLevelAlbums = [mediaSource mediaGroupForIdentifier:#"Albums"];
MLMediaGroup *allFotosAlbums = [mediaSource mediaGroupForIdentifier:#"Fotos"];
MLMediaGroup *iPhotoAlbums = [mediaSource mediaGroupForIdentifier:#"iPhotos"];
NSArray *albumList = [sharedAlbums.childGroups arrayByAddingObjectsFromArray:topLevelAlbums.childGroups];
albumList = [albumList arrayByAddingObjectsFromArray:allFotosAlbums.childGroups];
albumList = [albumList arrayByAddingObjectsFromArray:iPhotoAlbums.childGroups];
//albumList = [albumList arrayByAddingObjectsFromArray:#[topLevelAlbums]];
{
[self addObserver:self
forKeyPath:#"nextAlbumIndex"
options:0
context:#"nextAlbumIndex"]; // manages the loop over all albums
#pragma mark query all photos of one Album
//
MLMediaGroup *Nalbum = [[AlbumList objectAtIndex:nextAlbumIndex] group];
[Nalbum addObserver:self
forKeyPath:#"mediaObjects"
options:0
context:#"mediaObjects"];
[Nalbum mediaObjects]; // query the list and store result in Malbum
}}
}
I expect to retrieve the external Fotos library, but I always get the default one.
There is no error message, which could give me some hint.

Answer 1

After consulting Apple Support, I was told that reading Fotos library from another path than the default one is not yet supporrted.