I use Gaia with my iPhone. It works very well. Download maps from a few different sources/types of maps. There's power saving settings that allow a user to turn off GPS until activated, which really conserves the battery (as well as the usual battery saving tricks). I did a 5+-hour dayhike on Tiger and Sqwak Mtns., only pulling out the iPhone and activating the GPS when we weren't sure if we were still on the trail (deep snow, no other tracks, fun but exhausting), so maybe a dozen and a half times. Phone was always on. Still had over 90 percent battery level at the end of the hike.

Gaia online is pretty good too. You can plot your route and then download that to your phone, so when you check your position it shows it relative to your plotted route.

Find the program pretty easy to use. I'd recommend it.