Yes, I'm using Qt both on Android and iOS. Both work without glitches or quirks.
The same application I compile for Linux, Windows, OSX and Mobile Devices (only tablets, for big enterprise stuff) without significative changes on code (only a couple of #ifdefs for fullscreen and alike).
> Did you use one codebase to write the application?
Yes, only one codebase
> Do you need Mac OSX to compile for iOS or run emulator?
Unfortunately yes. I hope that in the future Apple will allow some sort of cross-compiling.
> Did you use C++ or is there a workaround to it?
Only C++ and Qt Widgets (no QML yet)
> Basically I'm hoping that new Qt can replace Intel XDK, RoboVM, Xamarin. However, the biggest hurdle is developing for iOS on a non-Mac machine.
It can replace (at least for my needs), but you will always need a Mac OSX to compile for iOS as far as I know (because of XCode dependency and licensing stuff)
Unreal Development Kit can deploy from windows to ios without buying a mac. I'm not sure if they made a deal with apple or if its possible without their approval.
I've been having fun writing apps in strict QML, intentionally. About every weekend I just take a traditional app use case and try writing it from scratch.
And surprisingly, the shortcoming is always documentation shortfalls. It took me digging through code samples to find out activeFocusItem is a thing, for example.
Just note you can't deploy QML only apps to mobile, you need a system with qmlscene installed already, but it is trivial to have a small C++ layer, and removing the JS only restriction gives you a huge amount more power over QML itself (building your own components in C++ vs combining them in JS).
The same application I compile for Linux, Windows, OSX and Mobile Devices (only tablets, for big enterprise stuff) without significative changes on code (only a couple of #ifdefs for fullscreen and alike).