Making apps like a keyboard

Question

If I wanted to make a mobile keyboard, which languages would I need to know and what software would I use?

I've searched it myself but I'm still not sure. To be completely clear I'm talking about keyboards like TouchPal or the SwiftKey Keyboard.

Answer 1

Java or kotlin pick any
Swift for IOS

Answer 2

You can use Android studio or Google's firebase to make one

Answer 3

Java and Kotlin are both languages yes? What about software?

Answer 4

Android studio this is IDE. Or framework Xamarin (C# supported).

For iOS - Swift & Objective-C

Or you can write programm in Python with framework Kivy (but it will not be a trivial solution)