Why would saving pictures to a Photo Library album require full Read-Write permissions instead of Add-Only?

I would like to save pictures to a user's device photo library. I want these pictures to be added to a specific photo album that I can create if it doesn't exist. To achieve that, I use:

Code Block swift
PHAssetCollectionChangeRequest.creationRequestForAssetCollection


I would assume this call would only need PHAccessLevel.addOnly permission, but this code crashes if my Info.plist misses the NSPhotoLibraryUsageDescription key.

Is it a bug or am I wrong to assume only NSPhotoLibraryAddUsageDescription should be required?
Why would saving pictures to a Photo Library album require full Read-Write permissions instead of Add-Only?
 
 
Q