This app
Whitney Guide Phone App was posted and then reposted
here on the Whitney Zone March 2014 It might be just what you're looking for. If I recall, you download the maps in advance and it uses your phone GPS. I'm a hard copy, compass and altimeter guy. On a steep obvious trail like Whitney, a calibrated altimeter gives the most important info you need - how much further to climb? To pinpoint your location, just find your contour line on the map. No need for more than that unless you stray off the trail, and that's what the map is for. Or just follow the wag bags left on the trail, your nose will guide you.
