There are no examples because it' simply C++ code you have to write.
For the battery level look at this class:
https://msdn.microsoft.com/en-us/library/windows.phone.devices.power.battery.aspx
Windows Store/Phone apps usually use C++/CX, an extension to C++. Probably you've seen something like:
SomeClass^ object = ref new SomeClass();
That's C++/CX code, it have a little different syntax than plain C++, but every example in the web is written in C++/CX.
So, where you now have your JNI-calls, put in C++/CX for WinRT.
But: Qt doesn't enable the C++/CX extension by default and QtCreator have no support for C++/CX.
I prefer to work with Visual Studio in this case. So, click in Visual Studio on your project --> Properties --> C++ --> General --> Consume Windows Runtime Extension --> Yes (/ZW). This will turn on the C++/CX extension for your code.
Feel free to ask further questions!
