New realization

https://github.com/mopsicus/UnityMobileInput

unity-keyboard-hack

Hack for hiding mobile input box on Android (iOS). Just adding invisible native inputfield and catch entered symbols. Dirty, but works.

If you know more beautiful solve - tell me.

Take a look at gameobject "Plugins" in the Demo scene, it requered for receive messages from plugin.

https://youtu.be/g2YR_NDA7i8