QuickLookThumbnailing iOS 13.0 Beta 1 to Beta 2 API Differences

QLThumbnailErrors.h
Added QLThumbnailErrorDomain
Added QLThumbnailError
Added QLThumbnailErrorGenerationFailed
Added QLThumbnailErrorSavingToURLFailed
Added QLThumbnailErrorNoCachedThumbnail
Added QLThumbnailErrorNoCloudThumbnail
Added QLThumbnailErrorRequestInvalid
Added QLThumbnailErrorRequestCancelled
QLThumbnailGeneratorErrors.h