[guava]

For those wanting Objective-C, Swift or C#, PaintCode [1] seems to support SVG conversion.

[1] http://www.paintcodeapp.com/

[seltzered]

another option is just keep the assets as SVG's and use a library to do the conversion (ios/osx specifically, I personally use SVGKit - https://github.com/SVGKit/SVGKit )