no i stand corrected... i must have been thinking of something else.
Those accessoryInputViews are not "standard"... the dev always has to implement himself.
It should, in theory be possible with the beta objc module... i spent a few minutes trying, and while i was able to get an accessoryInputView attached, it did not show up. But that may be because i was not using the right types.
You could also implement this sort of thing as an overlay that is tied to the kb frame, but that seems annoying perhaps.
It appears that with objc we can also change the kb Return button to a blue Done, or Go, etc, maybe that would scratch your itch?