[unity3d] What Language is Used To Develop Using Unity

As far as I know, you can go with c#.

You can also use the obscure language "Boo". (Found at https://boo-language.github.io/)

In the past (before about 2012) it was possible to use a strange variant of Java but that is now deprecated and does not work.

Note that Unity builds to Android / iOS, and many other platforms. The fact that iOS programming uses objective-c or Swift, is, completely irrelevant at the Unity3D level. Unity is programmed using c#.