Instead of looking to call Swift from C++ you should probably look at it the other way round. Use Swift as the main language for your development - it integrates beautifully with Interface Builder and is ideally suited for building a gui. You can then make calls to C/C++/Obj-C using the Swift bridging interfaces.
Admittedly there is a bit to learn but I think you'll find Swift to be quite easy to become familiar with. I have found C/C++ to be very useful in Swift applications for dealing with Posix/System interfaces, then passing results back to Swift either as arguments or via closure/callbacks.