Sketch 3 on Mac App Store is good at editing (can be better than PaintCode) and then exporting as SVG to PaintCode.
To get from PaintCode back to Sketch save as PDF and imports ok
https://itunes.apple.com/gb/app/sketch-3/id852320343?mt=12
Make sure canvas size in both is set to the same and in your views bounds else youll need to scale the context.
