Hello, I'm building apps for iPhone and iPad. Those are working together like a 2-screen Nintendo switch. Is there any way for communication between iPhone and iPad without an outside server? PAN(personal area network) could be a solution, but I could not find any information to use it for my case. If the iPad is connected to iPhone as a personal hotspot (though there's no cell tower), they should be communicate each other. I think there's a better way for my case. Could anyone can tell me where I start to looking for? Thanks, JJ