There are some Bluetooth mice that can be paired with an iOS device, for example the Citrix X1, or the Swiftpoint GT. These can be used in any app that supports them, like RDP clients, etc.
A majority of Bluetooth mice do not even pair with iOS. I believe this is what prevents them from being used by apps. If they could pair, then I guess communication with them could be implemented in apps individually.
Why is that? What makes the Citrix X1 able to pair with iOS, which is missing in other mice?
The Apple Bluetooth accessory design guidelines document does not mention that the device must implement any additional Apple specific command, in order to be able to pair.
I also don't believe that every dirt cheap Chinese Bluetooth accessory's manufacturer has had their device verified, and got some signed ID for it, or whatever.
What makes the difference then?