Unsupported sort descriptor in fetch options

It seems that I can not get a fetch result sorted by localIdentifier. Here is the code:

let sortDescriptor = NSSortDescriptor(key: "localIdentifier", ascending: true)
let options = PHFetchOptions()
options.sortDescriptors = [sortDescriptor]
let albums = PHCollection.fetchTopLevelUserCollections(with: options)
print(albums.count)

I've got this error:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unsupported sort descriptor in fetch options: (localIdentifier, ascending, compare:)'

However in Apple doc, localIdentifier can be used as key.

I've tried with PHAssetCollection.fetchAssetCollections, same problem, unable to use localIdentifier as key.