It was announced in CoreNFC Video on WWDC that starting from iOS 14 sendRequestWithFlag() command is available as a "write through" interface to transceive commands directly to a tag.
There was previously a method customCommandWithRequestFlag() however this was considered to be not working when Addressed Mode (Flag Byte bit mask 0x20) is used.
I must use addressed command according to NXP SLIX2 data sheet to authenticate at the tag.
So after customCommand..() was not working for me, I tried sendRequest...() but it is also not working, returning NFCError Code=102 "Stack Error" in the case where I consider to be the proper message.
The trick at ISO15693 protocol is that after each custom command there should come a byte equal to manufacturer ID. From my experiments I saw that customCommand..() method seem to add this byte by itself. So with this approach non-addressed commands do work.
In addressed mode, the full UID should come additionally after the manufacturer ID byte. It is not clear from description of the sendRequest() method if it will add anything on its own or not. Therefore I do not know which parameter I need to add and I experimented with adding/not adding manufacturer ID and/or UID but it either returns the error above or "transceive failed".
Is it possible to make open the behaviour inside the sendRequest()?
I have a proof that the command works with this tag because the same request executed on android works immediately.