tobii Eye tracker on ios

Hi I work as a rehab engineer at a rehabcenter in sweden, and some of my patients would greatly benefit from beeing able to use eye control for their ios and mac os devices.. as it is today tobii only works with windows devices and their explanation for this is that apple would not let the develop this for thir devices for some reason.. I wonder how you, apple, as the leading part of apps for disabled people, can have tured this opportunity down. ? if you would have let tobii to develop thier superb product for your product would create a new demand for ios, and erase the useage of window in tablets, or atleast minilize it to almost nothing. I feel bad when I have to tell my clients that, unfortunately they need to get rid of their macbooks and buy a windows PC instead.

And if this doesn't help, is there any other product that makes it possible for patients like mine, who lack movement in their limbs, to control their devices with their eye, I would very much appriciate any information.