The Tiīs did have real codenames:
400/500 MHz: Mercury
550/667 MHz: Onyx
667/800 MHz: Ivory
800/1000 MHz: Antimony
first Alīs: Thresher (12"), Hammerhead (17")
the more recent incarnations only have "Qxx" (xx: two digit number)
Only the early iBooks had codenames (the ones in the two color casings), codenames for ibooks were dropped with the "whiteBooks" (or shortly after)
Apple Museum