This is correct as of pre-iOS11. I have just set up my iPhone 8 and it appears to accept 24bit/96khz ALAC files but I have yet to confirm that it is *actually* playing it back at that resolution through the analogue pins of the Lightening connector (using the 3.5mm adapter that comes with the phone). I wouldn't be surprised if it downsamples to 48khz and/or still truncated 24bit to 16bit without telling you.