I was on approach, and hit send to tell an aircraft to switch to tower frequency, just as he switched on his own. App crashed as I hit send. I noticed he went from green to grey as I hit send. There was no way he did it that quickly as a result of my command, which is why I believe he changed on his own as I hit or just before I hit send.
I was using an IPAD Air, with 32G memory, and 8G free.