I usually implements google maps by calling google-maps api. Recently I decided to use google-maps plugin of 'Ionic Native' to make thing smoother. I have successfully implemented markers in maps and everything was working fine. But when I decided to implement routes between two points, I found that ionic native didn't have a function to implement this direction service.
So my question is
You can use Google Maps JavaScript API v3 for direction, then parse the result, and draw it using polyline and marker. Some people use the Google Directions API.
Or just launch the Google Maps application using https://github.com/dpa99c/phonegap-launch-navigator