So I recently learned here that HFS+ is case-insensitive but the APFS on iOS is case-sensitive. Is there a publically accessible documentation/reference which describes how APFS does handle upper/lower case file names on macOS? Or has somebody tried on Sierra already and can provide examples?
APFS has case-sensitive and case-insensitive variants. The case-insensitive variant of APFS is normalization-preserving, but not normalization-sensitive. The case-sensitive variant of APFS is both normalization-preserving and normalization-sensitive. Filenames in APFS are encoded in UTF-8 and aren’t normalized.
The first developer preview of APFS, made available in macOS Sierra in June 2016, offered only the case-sensitive variant. In macOS 10.12.4, the APFS developer preview was updated to also include a case-insensitive variant. In iOS 10.3, the case-sensitive variant of APFS is used.