First, I'm trying to determine if it is even technically feasible on the IOS platform or it is "locked out". Here's what I"m trying to accomplish
Build a device that will connect to the lightning port and allow passthrough charging. The device would allow the user to send various keyboard characters such as numbers, space, enter, arrows, etc. These characters would be used by applications on the ipad to control speech generating software such as proloquo2go, sonoflex, dynavox compass, etc. These applications use keyboard signals to control row-column scanning for disabled people using various types of accessible switches.
Bluetooth is not viable as it is too slow to respond to a user who can tap quickly.
The only device that is even close is the tapio by origin instruments. It uses an adapter to plug a usb device into the ios device but a "keyboards are not supported" or similar message pops up and stops input until the "ok" button is pressed. For a paralyzed user, this is a no-go situation.
There are other devices such as hook+ by ablenet that allow wired connections but these only use the IOS built-in switch control. Unfortunately, again, apple's closed system only allows for the built-in scanning patters which are not compatible with the row-column scanning systems available in the above mentioned applications.
Currently the only way to use row-column switch access software is to use a windows device. Given how friendly Apple usually is to the "alternative needs" and education community, I cannot believe this issue can't be surmounted. More than anything I need to talk to an apple engineer that can tell me, precisely, what needs to be done to build a switch adapter using the mfi program - or something else - to accomplish this task. I am very active in the disbled community and I assure you I am far from the only one that is frustrated by this roadblock with using IOS for switch controlled apps.