If you prefer Java check out Codename One: https://www.codenameone.com/ https://www.codenameone.com/ It's an open source project that compiles Java to all OS's

If you prefer Java check out Codename One: https://www.codenameone.com/ https://www.codenameone.com/ It's an open source project that compiles Java to all OS's including iOS, Windows (UWP), Android (obviously) as well as JavaScript (with threads etc.)